Vonjo (pacritinib citrate)

Dosage of pacritinib citrate is expressed in terms of pacritinib.

If adverse reactions occur during pacritinib therapy, temporary interruption of therapy, dosage reduction, and/or discontinuance of the drug may be necessary. If dosage reduction is required, the dosage of pacritinib should be reduced as described in Table 1.

Table 1: Recommended Dosage Reduction for Pacritinib Toxicity.

Dose Reduction Level Dosage Reduction after Recovery from Toxicity (Initial Dosage = 200 mg twice daily) First 100 mg twice daily Second 100 mg once daily Third Discontinue drug

The following table indicates the recommended dosage modification (i.e., temporary interruption of therapy, dosage reduction, discontinuance of therapy) for certain adverse effects according to severity.

Table 2. Dosage Modification for Pacritinib Toxicity.

Adverse Reaction and Severity Modification Diarrhea New onset: Initiate anti-diarrheal medications; encourage adequate oral hydration. Grade 3 or 4: Withhold therapy until diarrhea improves to grade 1 or lower or baseline; resume at last given dose. Intensify antidiarrheal medications and provide fluid rep lacement. If diarrhea recurs, withhold therapy until resolution to grade 1 or lower or baseline; resume therapy at 50% of the last dose once toxicity has resolved. Concomitant antidiarrheal treatment is required for patients resuming drug. Thrombocytopenia Clinically significant worsening of thrombocytopenia that lasts >7 days: Withhold therapy until thrombocytopenia resolves; resume at 50% of the last dosage. If toxicity recurs, withhold therapy until thrombocytopenia resolves; resume at 50% of the last dos age. Hemorrhage Moderate bleeding, intervention indicated: Withhold therapy until bleeding resolves; resume at same dosage. If hemorrhage recurs, withhold therapy until bleeding resolves; resume at 50% of the last dosage. Severe bleeding, transfusion, invasive interventi on, or hospitalization indicated: Withhold therapy until bleeding resolves; resume at 50% of the last dosage. If bleeding recurs, discontinue therapy. Life-threatening bleeding, urgent intervention indicated: Discontinue therapy. Prolonged QT Interval QTc prolongation >500 msec or >60 msec from baseline: Withhold therapy. If QTc prolongation resolves to <=480 msec or baseline within 1 week, resume at same dosage; if time to resolution is >1 week, resume therapy at a reduced dosage.

No dosing information is available for this tab.

No dosing information is available for this tab.

In vitro studies indicate that pacritinib is metabolized mainly by cytochrome P-450 (CYP) isoenzyme 3A4.

In vitro studies indicate pacritinib is a time dependent inhibitor of CYP1A2 and 3A4, and a reversible inhibitor of 3A4 and 2C19. The drug exhibits less potent inhibition of CYP1A2, 2B6, 2C8, 2C9, and 2D6.

In vitro studies indicate pacritinib is an inducer of CYP1A2 and 3A4.

Pacritinib is not a substrate of breast cancer resistance protein (BCRP), multidrug resistance-associated protein (MRP) 2, organic anion-transporters (OAT) 1 and 3, organic anion-transporting polypeptides (OATP) 1B1 and 1B3, organic cation transporters (OCT) 1 and 2, or P-glycoprotein (P-gp).

In vitro studies indicate pacritinib is an inhibitor of BCRP, OCT1, OCT2 (weak), and P-gp, but not an inhibitor of bile salt export pump (BSEP), MRP2, OAT1, or OAT3.

Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

Bcrp Inhibitors/Topotecan

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inhibitors of the BCRP transporter may increase the intestinal absorption and hepatic uptake of topotecan.(1)

CLINICAL EFFECTS: The concurrent administration of topotecan with an inhibitor of BCRP may result in elevated levels of topotecan and signs of toxicity. These signs may include but are not limited to anemia, diarrhea, and thrombocytopenia.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of topotecan states that the use of topotecan and BCRP inhibitors should be avoided. If concurrent use is warranted, carefully monitor patients for adverse effects.(1)

DISCUSSION: In clinical studies, the combined use of elacridar (100 mg to 1000 mg), a BCRP and P-gp inhibitor, increased the area-under-curve (AUC) of topotecan approximately 2.5-fold.(1) BCRP inhibitors linked to this monograph include: capmatinib, clopidogrel, curcumin, danicopan, dasabuvir, elbasvir, enasidenib, ensitrelvir, febuxostat, fostamatinib, fostemsavir, glecaprevir, grazoprevir, lazertinib, oteseconazole, pacritinib, paritaprevir, pibrentasvir, pirtobrutinib, regorafenib, resmetirom, ritonavir, roxadustat, tafamidis, ticagrelor, tolvaptan, turmeric, vadadustat, velpatasvir, voxilaprevir, and zongertinib.(2,3)

Cyp1a2 Inhibitors/Fezolinetant

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inhibitors of CYP1A2 may inhibit the metabolism of fezolinetant.(1-4)

CLINICAL EFFECTS: Concurrent use of a CYP1A2 inhibitor may increase levels of and adverse effects from fezolinetant.(1-4)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Recommendations for concurrent use of fezolinetant with CYP1A2 inhibitors differ in different regions. The US manufacturer of fezolinetant states that concurrent use with strong, moderate, and weak CYP1A2 inhibitors is contraindicated.(1) The Australian, Canadian, and UK manufacturers of fezolinetant state that concurrent use with strong and moderate CYP1A2 inhibitors is contraindicated, while weak CYP1A2 inhibitors are not predicted to cause clinically relevant changes in fezolinetant exposure.(2-4)

DISCUSSION: In a study, fluvoxamine, a strong CYP1A2 inhibitor, increased fezolinetant maximum concentration (Cmax) and area-under-curve (AUC) by 80% and 840%, respectively. Mexiletine (400 mg every 8 hours), a moderate CYP1A2 inhibitor, increased fezolinetant Cmax and AUC by 40% and 360%, respectively. Cimetidine (300 mg every 6 hours), a weak CYP1A2 inhibitor, increased fezolinetant Cmax and AUC by 30% and 100%, respectively.(1) Strong CYP1A2 inhibitors linked to this monograph include angelica root, ciprofloxacin, enasidenib, enoxacin, fluvoxamine, and rofecoxib. Moderate CYP1A2 inhibitors linked to this monograph include capmatinib, centanafadine, dipyrone, fexinidazole, genistein, hormonal contraceptives, methoxsalen, mexiletine, osilodrostat, phenylpropanolamine, pipemidic acid, rucaparib, troleandomycin, vemurafenib, and viloxazine. Weak CYP1A2 inhibitors linked to this monograph include acyclovir, allopurinol, artemisinin, belumosudil, caffeine, cannabidiol, cimetidine, curcumin, dan-shen, deferasirox, disulfiram, Echinacea, famotidine, ginseng, norfloxacin, obeticholic acid, parsley, piperine, propafenone, propranolol, ribociclib, simeprevir, thiabendazole, ticlopidine, triclabendazole, valacyclovir, verapamil, and zileuton.(5-7)

Cyp3a4 Inducers/Lumateperone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Lumateperone is a substrate of CYP3A4. Inducers of CYP3A4 may induce the metabolism of lumateperone.(1)

CLINICAL EFFECTS: The concurrent administration of a CYP3A4 inducer may decrease the exposure to lumateperone.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of lumateperone states that concurrent use with CYP3A4 inducers should be avoided.(1)

DISCUSSION: Coadministration of lumateperone with rifampin, a strong CYP3A4 inducer, resulted in a 98% reduction in area-under-curve (AUC) and a 90% reduction in concentration maximum (Cmax).(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, repotrectinib, rifabutin, telotristat, thioridazine, and tovorafenib.(2,3) Weak inducers of CYP3A4 include: amprenavir, armodafinil, aumolertinib, bexarotene, brivaracetam, clobazam, danshen, darolutamide, dexamethasone, dicloxacillin, echinacea, eslicarbazepine, garlic, genistein, gingko, ginseng, glycyrrhizin, nevirapine, omaveloxolone, oxcarbazepine, pioglitazone, quercetin, rufinamide, sotorasib, sulfinpyrazone, sunvozertinib, tecovirimat, terbinafine, ticlopidine, troglitazone, vemurafenib, and vinblastine.(2,3)

Cyp3a4 Inducers/Zuranolone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inducers of CYP3A4 may induce the metabolism of zuranolone.(1)

CLINICAL EFFECTS: Concurrent use of a CYP3A4 inducer may result in a loss of zuranolone efficacy.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of zuranolone with CYP3A4 inducers.(1)

DISCUSSION: Coadministration of zuranolone with rifampin decreased the maximum concentration (Cmax) by 0.31-fold and area-under-curve (AUC) by 0.15-fold.(1) Strong CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort. Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib. Weak CYP3A4 inducers linked to this monograph include: armodafinil, aumolertinib, bexarotene, brigatinib, brivaracetam, clobazam, danshen, darolutamide, dexamethasone, dicloxacillin, echinacea, eslicarbazepine, flucloxacillin, garlic, genistein, ginseng, glycyrrhizin, methylprednisolone, mobocertinib, nevirapine, omaveloxolone, oritavancin, oxcarbazepine, pioglitazone, pitolisant, quercetin, relugolix, rufinamide, sarilumab, sulfinpyrazone, sunvozertinib, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vemurafenib, vinblastine, and zanubrutinib.(2,3)

Dual Strong Or Moderate Cyp2c19 & Cyp3a4 Inducers/Mavacamten

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate inducers of CYP2C19 or CYP3A4 may increase the metabolism of mavacamten.(1-3)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP2C19 or CYP3A4 inducers with mavacamten may decrease the levels of and effectiveness of mavacamten.(1-3)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US and Canadian manufacturers of mavacamten state concurrent use of strong or moderate inducers of CYP2C19 or CYP3A4 is contraindicated.(1,2) The UK manufacturer of mavacamten states concomitant use with strong or moderate CYP2C19 or CYP3A4 inducers is dependent on CYP2C19 phenotype. Labeling recommends: -When initiating or increasing the dose of a strong CYP2C19 or CYP3A4 inducer in patients who are CYP2C19 poor metabolizers, monitor patients closely and adjust mavacamten dose based on clinical response. The maximum recommended dose of mavacamten is 5 mg daily. -When initiating or increasing the dose of a moderate CYP3A4 inducer in patients who are CYP2C19 poor metabolizers, monitor patients closely and adjust mavacamten dose based on clinical response. -When initiating or increasing the dose a strong or moderate CYP2C19 or strong CYP3A4 inducer in patients who are CYP2C19 intermediate, normal, rapid, or ultrarapid metabolizers, monitor patients closely and adjust mavacamten dose based on clinical response. -When discontinuing or decreasing the dose of a strong CYP2C19 or a strong or moderate CYP3A4 inducer in patients who are CYP2C19 poor metabolizers, decrease the dose of mavacamten from 5 mg to 2.5 mg, or pause therapy if dose is 2.5 mg. -When discontinuing or decreasing the dose of a strong CYP2C19 or CYP3A4 inducer in patients who are CYP2C19 intermediate, normal, rapid, or ultrarapid metabolizers, decrease the dose of mavacamten by one dose level when on doses of 5 mg or higher. Maintain mavacamten dose when on 2.5 mg. -When discontinuing or decreasing the dose of a moderate CYP2C19 inducer in patients who are CYP2C19 intermediate, normal, rapid, or ultrarapid metabolizers, no dose adjustment is warranted. Monitor patients closely and adjust mavacamten dose based on clinical response. -No dose adjustment is warranted with moderate CYP2C19 inducers in patients who are CYP2C19 poor metabolizers. -No dose adjustment is warranted with moderate CYP3A4 inducers in patients who are CYP2C19 intermediate, normal, rapid, or ultrarapid metabolizers.(3)

DISCUSSION: Concomitant use of mavacamten (a single 15 mg dose) with a strong CYP2C19 and CYP3A4 inducer (rifampin 600 mg daily dose) is predicted to decrease mavacamten area-under-curve (AUC) and maximum concentration (Cmax) by 87% and 22%, respectively, in CYP2C19 normal metabolizers, and by 69% and 4%, respectively, in CYP2C19 poor metabolizers. Drugs that induce both CYP2C19 and CYP3A4 linked to this monograph include: apalutamide, asunaprevir, dipyrone, efavirenz, enzalutamide, fosphenytoin, pacritinib, phenytoin, and rifampin.(4,5)

Moderate Cyp3a4 Inducers That Prolong Qt/Dordaviprone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Dordaviprone is a CYP3A4 substrate and has been shown to prolong the QTc interval. Moderate CYP3A4 inducers may induce the metabolism of dordaviprone. Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-3)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers that prolong QT may result in decreased levels and effectiveness of dordaviprone and increase the risk of potentially life-threatening arrhythmias including torsades de pointes.(1-3)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of dordaviprone states that the concurrent use of QT prolonging agents should be avoided. If current use cannot be avoided, separate administration of dordaviprone and the QT-prolonging agent. The manufacturer does not provide details about how to separate administration and states that the exposure-response relationship and time course of pharmacodynamic response is not fully characterized. Dordaviprone's time to maximum concentration (Tmax) occurs at 1.4 hours (0.5, 5.6 hours) and mean terminal half-life is 11 hours.(1) Concomitant use with moderate CYP3A4 inducers should also be avoided. Consider the use of alternative agents with less enzyme induction potential.(1) If concurrent use is necessary, baseline and periodic monitoring of ECG and electrolytes is recommended.(1) Increase the frequency of monitoring in patients with congenital long QT syndrome, existing QTc prolongation, history of ventricular arrhythmias, electrolyte abnormalities, or heart failure.(1) If QTc interval prolongation occurs, dose modifications are warranted. If QTc is >500 msec or the change from baseline is >60 msec, interrupt dordaviprone therapy until QTc interval is <= 480 msec or returns to baseline. If the patient has Torsades de pointes, polymorphic ventricular tachycardia, or signs or symptoms of serious or life-threatening arrhythmia, permanently discontinue dordaviprone.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Concurrent use of rifampin (a strong CYP3A4 inducer) is predicted to decrease dordaviprone maximum concentration (Cmax) by 68% and area-under-curve (AUC) by 83%. Concurrent use of efavirenz (a moderate CYP3A4 inducer) is predicted to decrease dordaviprone Cmax by 44% and AUC by 65%.(1) Dordaviprone causes concentration-dependent QTc interval prolongation. In a QT study, the estimated change in QTcF was 11.8 msec (90% CI: 9.8, 13.7) with dordaviprone at 1.2 times the maximum recommended dose.(1) In a pooled safety analysis, out of 82 patients with a post-baseline ECG, 6% of patients had an increase in QTc of >60 msec from baseline and 1.2% had an increase in QTc >500 msec.(1) Moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, fexinidazole, pacritinib, and thioridazine.(3)

Moderate Cyp3a4 Inducers That Prolong Qt/Ranolazine

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of ranolazine.(1,2) Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.(1,2)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of ranolazine and increased risk of QT prolongation. The risk of potentially life-threatening arrhythmias including torsades de pointes may be increased.(1,2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of ranolazine states that the concurrent use of CYP3A4 inducers such as rifampin, rifabutin, rifapentine, phenobarbital, phenytoin, carbamazepine, and St. John's wort is contraindicated. Concurrent use of moderate CYP3A4 inducers should be avoided.(1) The UK manufacturer of ranolazine states that ranolazine should not be used in patients receiving CYP3A4 inducers.(2) If coadministration with another agent that prolongs QT is unavoidable, monitor for prolongation of the QTc interval. When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Concurrent rifampin (600 mg daily), strong inducer of CYP3A4, decreased ranolazine plasma concentrations by 95%.(1,2) The effects of a moderate CYP3A4 inducer on ranolazine concentrations has not been studied. Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(4) Moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, fexinidazole, pacritinib, and thioridazine.(5,6)

Moderate Cyp3a4 Inducers That Prolong Qt/Revumenib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may induce the metabolism of revumenib by CYP3A4 and increase formation of the M1 metabolite which contributes to revumenib's effects on the QTc interval.(1) Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: Concurrent use of moderate CYP3A4 inducers may result in decreased levels and effectiveness of revumenib and increased risk of QT prolongation due to increased exposure to revumenib's M1 metabolite. The risk of potentially life-threatening arrhythmias including torsades de pointes may be increased.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of revumenib states that concomitant use of other drugs that may prolong the QTc interval should be avoided. In addition, concomitant use of moderate CYP3A4 inducers should be avoided. If concurrent use cannot be avoided, obtain ECGs prior to initiating revumenib, during concomitant use, and as clinically indicated.(1) If the QTc interval is greater than 480 ms, withhold revumenib therapy. Resume revumenib after the QTc interval drops to 480 msec or less.(1) If coadministration with another agent that prolongs QT is unavoidable, monitor for prolongation of the QTc interval.(1) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Revumenib is primarily metabolized by CYP3A4. Concomitant use of a moderate CYP3A4 inducer may decrease revumenib concentrations and increase M1 systemic exposure, resulting in decreased revumenib efficacy or increased risk of QT prolongation.(1) In clinical trials, QTc interval prolongation was reported as an adverse event in 29% of 135 patients treated with the recommended dosage of revumenib; 12% of patients had Grade 3 QTc prolongation. Revumenib increased the QTc interval in a concentration-dependent manner. At the mean steady-state Cmax using the highest approved recommended dosage of revumenib without CYP3A4 inhibitors, QTc increase was predicted to be 27 msec (upper bound of 90% confidence interval = 30 msec). At the steady-state Cmax using the highest approved recommended dosage of revumenib with CYP3A4 inhibitors, QTc increase was predicted to be 19 msec (upper bound of 90% confidence interval = 22 msec).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3) Moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, fexinidazole, pacritinib, and thioridazine.(4)

Moderate Cyp3a4 Inducers That Prolong Qt/Taletrectinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate CYP3A4 inducers that prolong QT may induce the metabolism of taletrectinib and result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers that prolong QT may result in decreased levels and effectiveness of taletrectinib and have additive effects on the QTc interval, which may result in potentially life-threatening arrhythmias including torsade de pointes.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Taletrectinib should be taken on an empty stomach. Administration with food may increase the risk of QT prolongation or torsade de pointes.

PATIENT MANAGEMENT: The manufacturer of taletrectinib states that concomitant use of moderate CYP3A4 inducers should be avoided.(1) The manufacturer of taletrectinib states that the concurrent use of QT prolonging agents should be avoided. If concurrent use cannot be avoided, obtain ECGs prior to initiating taletrectinib, during concomitant use, and as clinically indicated.(1) If concurrent therapy is warranted, correct any electrolyte abnormalities and instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Taletrectinib is primarily metabolized by CYP3A4.(1) Concomitant administration of taletrectinib with a moderate inducer (efavirenz) is predicted to decrease in taletrectinib area under the curve (AUC) and maximum concentration (Cmax) by 66% and 40%, respectively.(1) Concomitant administration of taletrectinib with a strong inducer (rifampin; 600 mg once daily) resulted in a decrease in taletrectinib area under the curve (AUC) and maximum concentration (Cmax) by 86% and 42%, respectively.(1) The effect of taletrectinib on the QTc interval was evaluated in a pooled safety population of 351 patients receiving taletrectinib (600 mg orally once daily) and underwent at least one post ECG assessment. 13% experienced an increase in QTcF of greater than 60 msec compared to baseline and 2.6% had a QTcF increase of greater than 500 msec. A concentration-dependent QTc prolongation effect of taletrectinib was observed. The largest mean increase in the QTc interval was 12.8 msec (upper CI 15.4 msec) at Cmax. The predicted increase in the QTC interval with high fat food is 20.5 msec.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QT interval. Agents linked to this monographs have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsade de pointes in clinical trials and/or postmarketing reports.(3) Moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, fexinidazole, pacritinib, and thioridazine.(3,4)

Moderate Cyp3a4 Inducers That Prolong Qt/Zidesamtinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Zidesamtinib is a CYP3A4 substrate and has been shown to prolong the QTc interval. Moderate CYP3A4 inducers may induce the metabolism of zidesamtinib.(1) Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-2)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers that prolong QT may result in decreased levels and effectiveness of zidesamtinib and increase the risk of potentially life-threatening arrhythmias including torsades de pointes.(1-2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of zidesamtinib states that concurrent use of moderate CYP3A4 inducers should be avoided.(1) The manufacturer of zidesamtinib also states that concurrent use of other drugs that are known to prolong the QTc interval should be monitored more frequently.(1) If concurrent use is warranted, monitor ECG and electrolytes when initiating zidesamtinib, during concurrent use, and as clinically indicated. Consider increasing the frequency of ECG and electrolyte monitoring. Withhold, then resume at same or reduced dose, or permanently discontinue zidesamtinib based on severity.(1) If QTc prolongation occurs, follow recommended dose modifications: - Grade 2 (QTc interval 481-500 ms): Withhold zidesamtinib until recovery to Grade <= 1 or baseline; correct electrolytes and/or change concomitant medications; and resume at same dose. - Grade 3 (QTc interval >= 501 ms or QTc interval increase of > 60 ms from baseline): Withhold zidesamtinib until recovery to Grade <= 1 or baseline; correct electrolytes and/or change concomitant medications; and resume at reduced dose. - Grade 4 (Torsades de pointes; polymorphic ventricular tachycardia; or signs/symptoms of serious arrhythmia): Permanently discontinue zidesamtinib. Consider obtaining serum calcium, magnesium, and potassium levels and correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Zidesamtinib is a CYP3A4 substrate.(1) Zidesamtinib 100 mg once daily increased the QTc by 13 ms (upper confidence interval = 19 ms) in patients with advanced ROS1-positive NSCLC and other advanced ROS1-positive solid tumors.(1) In a pooled safety study, QTc increase >60 ms occurred in 2% of patients and 0.2% of patients had an increase in QTcF > 500 ms.(1) Moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, fexinidazole, pacritinib, and thioridazine.(3,4)

Moderate Cyp3a4 Inducers That Prolong Qt/Ziftomenib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Ziftomenib is a CYP3A4 substrate and has been shown to prolong the QTc interval. Moderate CYP3A4 inducers may induce the metabolism of ziftomenib.(1) Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.(1-2)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers that prolong QT may result in decreased levels and effectiveness of ziftomenib and increase the risk of potentially life-threatening arrhythmias including torsades de pointes.(1-2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of ziftomenib states that co-administration with moderate inducers of CYP3A4 should be avoided. Monitor patients for loss of efficacy or consider the use of alternative medicinal products.(1) The manufacturer of ziftomenib states that the concurrent use of QT prolonging agents should be avoided. If concurrent use cannot be avoided, obtain ECGs prior to initiating ziftomenib, during concomitant use, and as clinically indicated. More frequent ECG monitoring may be necessary. Do not initiate ziftomenib if baseline QTcF > 480 ms.(1) Perform ECG at least once weekly for the first 4 weeks on treatment, then at least monthly thereafter. If the QTc interval is greater than 500 ms or the change from baseline is greater than 60 ms, withhold ziftomenib therapy.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Rifampin (strong CYP3A4 inducer) is estimated to decrease ziftomenib area-under-curve (AUC) by up to 80% and maximum concentration (Cmax) by up to 70%.(1) In clinical trials, QTc interval prolongation was reported as an adverse event in 12% of 112 patients treated with the recommended dosage of ziftomenib. QTc was >500 ms in 9% of patients and the increase from baseline QTcF was >60 ms in 12% of patients. Ziftomenib increased the QTc interval in a concentration-dependent manner. At a dose of 600 mg daily, the largest mean increase in QTc was 7.7 ms (upper bound of confidence interval = 12.6 ms).(1) Moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, fexinidazole, pacritinib, thioridazine.(3,4)

Moderate Cyp3a4 Inducers/Atrasentan

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of atrasentan.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may reduce the clinical effectiveness of atrasentan.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of atrasentan states that concurrent use of moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: In a study, atrasentan trough concentration (Ctrough) decreased by 90% following coadministration of a single dose of 10 mg of atrasentan with rifampin (strong CYP3A4 inducer).(1) The effects of a moderate CYP3A4 inducer on atrasentan concentrations has not been studied. Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Daraxonrasib (< 400 Mg)

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Daraxonrasib is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of daraxonrasib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of daraxonrasib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of daraxonrasib states that concomitant use of moderate CYP3A4 inducers requires a dose increase of daraxonrasib to 400 mg once daily.(1)

DISCUSSION: In a clinical study, daraxonrasib area-under-curve (AUC) is predicted to decrease by 50-84% with concomitant use of efavirenz 600 mg once daily and modafinil 400 mg once daily (moderate CYP3A4 inducers).(1) Moderate CYP3A4 inducers linked to this monograph include: asunaprevir, belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lopinavir, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, telotristat, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Defactinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may accelerate the metabolism of defactinib by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of defactinib and a moderate CYP3A4 inducer may result in decreased levels and effectiveness of defactinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of defactinib states that the concurrent use of moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: The impact of moderate CYP3A4 inhibitors on the pharmacokinetics of defactinib has not been investigated in clinical studies. In a study, defactinib maximum concentration (Cmax) decreased by 83% and area-under-curve (AUC) by 87% following coadministration with phenytoin (strong CYP3A4 inducer) three times daily for 23 days and a single dose of defactinib 200 mg (1.0 times the approved recommended dose) on Day 14. The AUC and Cmax of N-desmethyl amide (M4), a major active metabolite of defactinib, decreased by 79% and 70%, respectively.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(2)

Moderate Cyp3a4 Inducers/Fruquintinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of fruquintinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of fruquintinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: If possible, avoid concurrent use of moderate inducers of CYP3A4 with fruquintinib. If concurrent use cannot be avoided, continue to administer fruquintinib at the recommended dosage.(1)

DISCUSSION: Concomitant use with efavirenz (moderate CYP3A4 inducer) is predicted to decrease the fruquintinib maximum concentration (Cmax) by 4% and the area-under-curve (AUC) by 32%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Iberdomide

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Iberdomide is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of iberdomide.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of iberdomide.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of iberdomide states that concomitant use of moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: In a PBPK model in patients with cancer, iberdomide area-under-curve (AUC) was predicted to be decreased by 30% and maximum concentration (Cmax) by 50% following concomitant use with efavirenz (moderate CYP3A4 inducer).(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Lazertinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of lazertinib via this pathway.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may reduce the clinical effectiveness of lazertinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of lazertinib states that concurrent use of moderate CYP3A4 inducers should be avoided. Consider an alternative concomitant medication with no potential to induce CYP3A4.(1)

DISCUSSION: In a pharmacokinetic modelling study, concomitant use of efavirenz (moderate CYP3A4 inducer) is predicted to decrease lazertinib steady state concentration maximum (Cmax) and area-under-curve (AUC) by at least 32% and 44%, respectively.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Lirafugratinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of lirafugratinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of lirafugratinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of moderate CYP3A4 inducers with lirafugratinib.(1)

DISCUSSION: In a pharmacokinetic model, efavirenz (a moderate CYP3A4 inducer) 600 mg daily for 19 days is predicted to reduce lirafugratinib area-under-the-curve (AUC) by 57% and maximum concentration (Cmax) by 15%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Nerandomilast (9 Mg)

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may induce the metabolism of nerandomilast by CYP3A4.

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may reduce the clinical effectiveness of nerandomilast.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The recommended dose of nerandomilast with moderate CYP3A4 inducers is 18 mg twice daily. For patients who are unable to tolerate 18 mg twice daily, do not reduce the dosage to 9 mg twice daily in patients taking moderate CYP3A4 inducers.(1)

DISCUSSION: Nerandomilast is primarily metabolized by CYP3A4.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Olverembatinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Olverembatinib is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of olverembatinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of olverembatinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of olverembatinib states that co-administration with moderate inducers of CYP3A4 should be avoided.(1)

DISCUSSION: In a clinical study of 15 healthy subjects, rifampin (600 mg daily for 8 days), a strong CYP3A4 inducer, decreased the area-under-curve (AUC) and maximum concentration (Cmax) of single-dose olverembatinib 40 mg by 75.19% and 61.27%, respectively.(2) In a PBPK model, efavirenz (600 mg daily for 8 days), a moderate CYP3A4 inducer, decreased the AUC and Cmax of olverembatinib 40 mg by 65% and 52%, respectively.(3) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(4,5)

Moderate Cyp3a4 Inducers/Oveporexton

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Oveporexton is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of oveporexton.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of oveporexton.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of oveporexton states that concomitant use of moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: In a PBPK model, oveporexton area-under-curve (AUC) was predicted to be decreased by 73% and maximum concentration (Cmax) by 55% following concomitant use of a moderate CYP3A4 inducer.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Pyrotinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of pyrotinib.(1)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of pyrotinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of pyrotinib states that coadministration with moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: In a study of healthy subjects, concurrent use of rifampin (a strong CYP3A4 inducer) decreased pyrotinib area-under-curve (AUC) by 96% and maximum concentration (Cmax) by 89%.(1) In a study of healthy subjects, concurrent use of efavirenz (a moderate CYP3A4 inducer) decreased pyrotinib AUC by 80% and Cmax by 66%.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Remibrutinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may induce the metabolism of remibrutinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may alter the clinical effectiveness of remibrutinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of remibrutinib with moderate CYP3A4 inducers.(1) Monitor patients receiving concurrent therapy for reduced efficacy.

DISCUSSION: Remibrutinib is primarily metabolized by CYP3A4.(1) Remibrutinib concentration maximum (Cmax) is predicted to decrease by approximately 60% and area-under-curve (AUC) is predicted to decrease by approximately 64% following concomitant administration with efavirenz (a moderate CYP3A4 inducer) 600 mg once daily for 14 days.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Sevabertinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Sevabertinib is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of sevabertinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of sevabertinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of sevabertinib states that co-administration with moderate inducers of CYP3A4 should be avoided. Monitor patients for loss of efficacy or consider the use of alternative medicinal products.(1)

DISCUSSION: In a study, carbamazepine (strong CYP3A4 inducer) decreased sevabertinib's area-under-curve (AUC) 79% and maximum concentration (Cmax) 57%.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Sonrotoclax

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Sonrotoclax is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of sonrotoclax.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of sonrotoclax.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of sonrotoclax states that co-administration with moderate inducers of CYP3A4 should be avoided.(1)

DISCUSSION: The impact of moderate CYP3A4 inducers on the pharmacokinetics of sonrotoclax has not been investigated in clinical studies. In a clinical study, sonrotoclax area-under-curve (AUC) decreased by 65% and maximum concentration (Cmax) by 42% following concomitant use of phenytoin (strong CYP3A4 inducer).(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Suzetrigine

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of suzetrigine.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may reduce the clinical effectiveness of suzetrigine.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of suzetrigine states that concurrent use of moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: Concomitant administration of efavirenz (moderate CYP3A inducer) with suzetrigine is predicted to decrease suzetrigine and active metabolite M6-SUZ area-under-curve (AUC) by 63% and 60%, respectively, while suzetrigine maximum concentration (Cmax) is predicted to decrease by 29% and M6-SUZ Cmax is predicted to increase by 1.3-fold, respectively.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Venetoclax

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of venetoclax.(1)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of venetoclax.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of venetoclax states that the concurrent use of CYP3A4 inducers should be avoided, and that alternative treatments with less CYP3A4 induction should be considered.(1)

DISCUSSION: In a study with 10 healthy subjects, co-administration of rifampin (600 mg daily for 13 days), decreased venetoclax area-under-curve (AUC) by 71% and maximum concentration (Cmax) by 42%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, telotristat, thioridazine, tipranavir/ritonavir, and tovorafenib.(2-3)

Moderate Cyp3a4 Inducers/Zilurgisertib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of zilurgisertib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of zilurgisertib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of moderate CYP3A4 inducers with zilurgisertib.(1)

DISCUSSION: In a pharmacokinetic model, efavirenz (a moderate CYP3A4 inducer) is predicted to decrease zilurgisertib area-under-the-curve (AUC) by 60% and maximum concentration (Cmax) by 25%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Zoliflodacin

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Zoliflodacin is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of zoliflodacin.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of zoliflodacin.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of zoliflodacin states that co-administration with moderate inducers of CYP3A4 is contraindicated.(1)

DISCUSSION: Efavirenz, a moderate CYP3A4 inducer, is predicted to decrease the area-under-curve (AUC) of zoliflodacin by approximately 41%.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

P-Gp Or Bcrp Inhibitors That Prolong Qt/Pazopanib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Concurrent use with other agents that prolong the QTc interval and inhibit P-gp or BCRP may result in increased absorption and higher levels of pazopanib and additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of pazopanib with other agents that prolong the QTc interval and inhibit P-gp or BCRP may result in elevated levels of pazopanib, signs of toxicity, and potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The US manufacturer of pazopanib states concurrent use of strong P-gp or BCRP inhibitors should be avoided. Use caution when pazopanib is coadministered with other drugs known to prolong the QTc interval.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Administration of 1,500 mg lapatinib, a substrate and weak inhibitor of CYP3A4, P-gp, and BCRP, with 800 mg pazopanib resulted in an approximately 50% to 60% increase in mean pazopanib area-under-curve (AUC) and maximum concentration (Cmax) compared with administration of 800 mg pazopanib alone.(1) In clinical studies, 2% (11/558) of patients receiving pazopanib experienced QT prolongation. Torsades de pointes occurred in less than 1% (2/977) of patients who received pazopanib in monotherapy studies. In a randomized clinical trial, 3 of 290 patients who received pazopanib had post-baseline QTc values between 500 and 549 msec. None of the patients receiving placebo had post-baseline QTc values greater than or equal to 500 msec.(1) A retrospective review of 618 cancer patients treated with 902 administrations of tyrosine kinase inhibitors were evaluated for rate and incidence of QTc prolongation. In patients who received pazopanib, QTc prolongation was identified in 32 (19.4%) with 18 (56.3%) having Grade 1 (QTc 450-480 ms) and 4 (12.5%) having Grade 2 (QTc 480-500 ms). Grade 3 events occurred in 3 (9.3%) having QTc greater than or equal to 500 ms and 4 (12.5%) having QTc change greater than or equal to 60 ms. Ventricular tachycardia was seen in 2 (6.3%) of patients and 1 (3.1%) patient experienced sudden cardiac death.(4) Agents that are P-gp or BCRP inhibitors that may cause QT prolongation include: amiodarone, aumolertinib, azithromycin, dronedarone, erythromycin, hydroquinidine, lapatinib, mavorixafor, osimertinib, pacritinib, propafenone, quinidine, ranolazine, selpercatinib, vemurafenib, and vepdegestrant.(3, 5-6)

Pacritinib/Crizotinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Crizotinib is a substrate and moderate inhibitor of CYP3A4.(1) Pacritinib is a substrate and moderate inducer of CYP3A4.(2) Agents that induce the CYP3A4 isoenzyme may induce the metabolism of crizotinib.(1) Moderate CYP3A4 inhibitors may inhibit the CYP3A4 mediated metabolism of pacritinib.(2) Crizotinib and pacritinib have been observed to prolong the QTc interval. Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.

CLINICAL EFFECTS: Concurrent use of crizotinib and pacritinib may decrease the levels and effectiveness of crizotinib(1) while increasing levels and toxicity of pacritinib.(2) Concurrent use may result in additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(1) Other toxicities of pacritinib include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) CYP2B6 genotype may also increase the risk of this interaction. Patients who are most susceptible to this interaction are patients who are CYP2B6 poor metabolizers with CYP2B6 *6/*6 allele.(4) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The concurrent use of crizotinib and pacritinib should be avoided.(1) If concurrent use cannot be avoided, monitor patients for increased adverse reactions from pacritinib and consider pacritinib dose modifications based on safety.(2) If coadministration is unavoidable, monitor for prolongation of the QTc interval.(1,2) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. In patients who develop a QTc greater than 500 ms on at least 2 separate ECGs, withhold crizotinib until recovery to baseline or to a QTc less than 481 ms, then resume crizotinib at reduced dose.(1) In patients who develop a QTc greater than 500 ms or greater than or equal to 60 ms change from baseline with torsade de pointes or polymorphic ventricular tachycardia or signs/symptoms of serious arrhythmia, permanently discontinue crizotinib.(1) If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(2)

DISCUSSION: Rifampin (600 mg daily), a strong CYP3A4 inducer, decreased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of crizotinib (250 mg) by 69% and 82%, respectively.(1) Clarithromycin (500 mg twice daily for 5 days, a strong CYP3A4 inhibitor) increased Cmax and AUC of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(2) Crizotinib is associated with concentration-dependent QTc interval prolongation. In a clinical trial 2.1% of patients were found to have a QTcF greater than or equal to 500 msec and 5% of patients had an increase in QTcF by greater than or equal to 60 msec.(1) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(2) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(2)

Pacritinib/Fedratinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Fedratinib is a substrate and moderate inhibitor of CYP3A4.(1) Pacritinib is a substrate and moderate inducer of CYP3A4.(2) Agents that induce the CYP3A4 isoenzyme may induce the metabolism of fedratinib.(1) Moderate CYP3A4 inhibitors may inhibit the CYP3A4 mediated metabolism of pacritinib.(2)

CLINICAL EFFECTS: Concurrent use of fedratinib and pacritinib may decrease the levels and effectiveness of fedratinib(1) while increasing levels and toxicity of pacritinib.(2) Elevated levels of pacritinib may result in QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(2) Other toxicities of pacritinib include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The concurrent use of fedratinib and pacritinib should be avoided.(1,2) If concurrent use cannot be avoided, monitor patients for increased adverse reactions from pacritinib and consider pacritinib dose modifications based on safety.(2) If coadministration is unavoidable, monitor for prolongation of the QTc interval.(1,2) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(2)

DISCUSSION: Coadministration of efavirenz (moderate CYP3A4 inducer: 600 mg once daily) with a single dose of fedratinib (500 mg; 1.25 times the recommended dose) decreased the area-under-curve (AUC) of fedratinib by approximately 47%.(1) Clarithromycin (500 mg twice daily for 5 days, a strong CYP3A4 inhibitor) increased the maximum concentration (Cmax) and AUC of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(2) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(2) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(2)

Pacritinib/Hormonal Contraceptives

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Pacritinib is a moderate CYP3A4 inducer. Coadministration of pacritinib with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of pacritinib may reduce the effectiveness of hormonal contraceptives, except for intrauterine systems containing levonorgestrel.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of pacritinib states to avoid concomitant use with hormonal contraceptives except for intrauterine systems containing levonorgestrel. If contraception is needed or desired, an alternate contraceptive that is not affected by CYP3A4 inducers (e.g., an intrauterine system) or additional non-hormonal contraceptives (e.g., condoms) should be used when treated concomitantly with pacritinib and for 30 days after the last dose of pacritinib.(1) Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(2)

DISCUSSION: Pacritinib is a moderate CYP3A4 inducer.(1) Coadministration of pacritinib (200 mg twice daily at steady state) with a single dose of oral midazolam (2 mg) (a CYP3A4 substrate) decreased the concentration maximum (Cmax) and area-under-curve (AUC) of midazolam by 60% and 60%, respectively.(1)

Pacritinib/Idelalisib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Pacritinib is a substrate of CYP3A4.(1) Strong CYP3A4 inhibitors such as idelalisib may inhibit the CYP3A4 mediated metabolism of pacritinib.(1) Idelalisib is a substrate of CYP3A4. Moderate CYP3A4 inducers such as pacritinib may induce the metabolism of idelalisib.(2)

CLINICAL EFFECTS: Concurrent use of pacritinib with an inhibitor of CYP3A4 may result in elevated levels of and toxicity from pacritinib.(1) Elevated levels of pacritinib may result in QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP). Other toxicities include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(1) Concurrent use of moderate CYP3A4 inducers may decrease the levels and effectiveness of idelalisib.(2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3)

PATIENT MANAGEMENT: The concurrent use of pacritinib with idelalisib is contraindicated.(1) If concurrent use is warranted, monitor for prolongation of the QTc interval.(1) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(1)

DISCUSSION: Clarithromycin (500 mg twice daily for 5 days) increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(1) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) In a study in healthy subjects, rifampin (600 mg daily for 8 days) decreased the concentration maximum (Cmax) and area-under-curve (AUC) of idelalisib (150 mg single dose) by 58% and 75%, respectively.(3)

Pacritinib/Lonafarnib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Lonafarnib is a substrate and strong inhibitor of CYP3A4.(1) Pacritinib is a substrate and moderate inducer of CYP3A4.(2) Agents that induce the CYP3A4 isoenzyme may induce the metabolism of lonafarnib.(1) Strong CYP3A4 inhibitors may inhibit the CYP3A4 mediated metabolism of pacritinib.(2) Lonafarnib and pacritinib have been observed to prolong the QTc interval. Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.

CLINICAL EFFECTS: Concurrent use of lonafarnib and pacritinib may decrease the levels and effectiveness of lonafarnib(1) while increasing levels and toxicity of pacritinib.(2) Concurrent use may result in additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(1) Other toxicities of pacritinib include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The concurrent use of pacritinib with lonafarnib is contraindicated.(2) If concurrent use is warranted, monitor ECG prior to initiation, during concurrent therapy, and as clinically indicated.(1,2) If coadministration is unavoidable, monitor for prolongation of the QTc interval.(1) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(1)

DISCUSSION: The combination of lonafarnib and pacritinib has not been investigated in clinical studies. With coadministration of a single oral dose of 50 mg lonafarnib (combined with a single oral dose of 100 mg ritonavir) following 600 mg rifampin (a strong CYP3A4 inducer) for 8 days, the area-under-curve (AUC) was reduced by 98% and the maximum concentration (Cmax) was reduced by 92%.(1) Clarithromycin (500 mg twice daily for 5 days, strong CYP3A4 inhibitor) increased Cmax and AUC of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(2) In a thorough QT study, lonafarnib 200 mg twice daily for 9 consecutive days and a single 200 mg dose on day 10 increased the mean QTc interval by 19 msec (upper bound of 90% confidence interval = 27 msec) on day 10 at 48 hours after administration of the morning dose of lonafarnib 200 mg. The maximum concentration (Cmax) on Day 10 was 2233 ng/ml, which is similar to the mean Cmax of 2695 ng/ml observed in the Hutchinson-Gilford Progeria Syndrome patient population.(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(2)

Pacritinib/Rilzabrutinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Rilzabrutinib is a substrate and moderate inhibitor of CYP3A4.(1) Pacritinib is a substrate and moderate inducer of CYP3A4.(2) Agents that induce the CYP3A4 isoenzyme may induce the metabolism of rilzabrutinib.(1) Moderate CYP3A4 inhibitors may inhibit the CYP3A4 mediated metabolism of pacritinib.(2)

CLINICAL EFFECTS: Concurrent use of rilzabrutinib and pacritinib may decrease the levels and effectiveness of rilzabrutinib(1) while increasing levels and toxicity of pacritinib.(2) Elevated levels of pacritinib may result in QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(2) Other toxicities of pacritinib include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The concurrent use of rilzabrutinib and pacritinib should be avoided.(1,2) If concurrent use cannot be avoided, monitor patients for increased adverse reactions from pacritinib and consider pacritinib dose modifications based on safety.(2) If coadministration is unavoidable, monitor for prolongation of the QTc interval.(1,2) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(2)

DISCUSSION: Concomitant administration of rilzabrutinib with efavirenz or rifabutin (moderate CYP3A4 inducers) is predicted to decrease rilzabrutinib area under the curve (AUC) and maximum concentration (Cmax) by up to 70% at steady state.(1) Clarithromycin (500 mg twice daily for 5 days, a strong CYP3A4 inhibitor) increased the Cmax and AUC of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(2) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(2) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(2)

Pacritinib/Rosuvastatin (> 20 Mg)

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Pacritinib is an inhibitor of the BCRP transporter, which may result in increased absorption and decreased hepatic uptake of rosuvastatin.(1-3)

CLINICAL EFFECTS: Concurrent use of pacritinib with rosuvastatin may result in increased levels and side effects from rosuvastatin, including myopathy and rhabdomyolysis.(1-2)

PREDISPOSING FACTORS: The risk for myopathy or rhabdomyolysis may be greater in patients 65 years and older, inadequately treated hypothyroidism, renal impairment, carnitine deficiency, malignant hyperthermia, or in patients with a history of myopathy or rhabdomyolysis. Patients with a SLCO1B1 polymorphism that leads to decreased function of the hepatic uptake transporter OATP1B1 may have increased statin concentrations and be predisposed to myopathy or rhabdomyolysis. Patients on rosuvastatin with ABCG2 polymorphisms leading to decreased or poor BCRP transporter function may have increased rosuvastatin concentrations and risk of myopathy.

PATIENT MANAGEMENT: The manufacturer of pacritinib states that the dose of rosuvastatin should not exceed 20 mg daily when used concurrently.(1) Monitor patients closely for signs and symptoms of toxicity from increased rosuvastatin concentrations.(1,2)

DISCUSSION: Concurrent use of pacritinib (200 mg twice daily at steady state) increased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of rosuvastatin (5 mg) by 200% and 80%, respectively.(1)

Pacritinib/Strong Cyp3a4 Inducers

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Agents that induce the CYP3A4 isoenzyme may induce the metabolism of pacritinib.(1)

CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inducers may decrease the levels and effectiveness of pacritinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The use of strong CYP3A4 inducers in patients receiving therapy with pacritinib is contraindicated.(1) Consider the use of alternative agents with less enzyme induction potential.(1)

DISCUSSION: Rifampin (600 mg daily for 10 days), a strong CYP3A4 inducer, decreased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of pacritinib (400 mg) by 51% and 87%, respectively.(1) Strong CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, carbamazepine, enzalutamide, fosphenytoin, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2)

Pacritinib/Strong Cyp3a4 Inducers That Prolong Qt

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Apalutamide and ivosidenib may induce the metabolism of pacritinib and result in additive risk of QT prolongation.(1)

CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inducers that prolong QT may decrease the levels and effectiveness of pacritinib and increase the risk of potentially life-threatening arrhythmia, including torsade de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The use of strong CYP3A4 inducers that prolong QT in patients receiving therapy with pacritinib is contraindicated.(1) Consider the use of alternative agents with less enzyme induction potential.(1) If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose.(1) If concurrent use is necessary, consider electrocardiogram (ECG) and electrolyte monitoring (calcium, magnesium, and potassium levels) at baseline and regular intervals.(1) Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Rifampin (600 mg daily for 10 days), a strong CYP3A4 inducer, decreased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of pacritinib (400 mg) by 51% and 87%, respectively.(1) In a 24 week clinical study, patients treatment with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(4) Strong CYP3A4 inducers that prolong QT linked to this monograph include: encorafenib and ivosidenib.(2)

Pacritinib/Strong Cyp3a4 Inhibitors

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Agents that inhibit the CYP3A4 isoenzyme may inhibit the metabolism of pacritinib.(1)

CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inhibitors may increase the levels and effects of pacritinib.(1) Elevated levels of pacritinib may result in QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP). Other toxicities include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The use of strong CYP3A4 inhibitors is contraindicated in patients undergoing therapy with pacritinib.(1) Consider alternatives with no or minimal enzyme inhibition. If coadministration with a strong CYP3A4 inhibitor is unavoidable, monitor for prolongation of the QTc interval.(1) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(1)

DISCUSSION: Clarithromycin (500 mg twice daily for 5 days) increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(1) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Strong inhibitors of CYP3A4 include: boceprevir, cobicistat, ensitrelvir, indinavir, itraconazole, josamycin, ketoconazole, mibefradil, mifepristone, nefazodone, nelfinavir, nirmatrelvir/ritonavir, paritaprevir, relacorilant, telaprevir, tipranavir, troleandomycin, and tucatinib.(3,4)

Pacritinib/Strong Cyp3a4 Inhibitors That Prolong Qt

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong inhibitors of CYP3A4 that prolong the QTc interval may inhibit the metabolism of pacritinib and result in additive risk of QT prolongation.(1)

CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inhibitors that prolong the QTc interval may increase the levels and effects of pacritinib, including additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(1) Other toxicities include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The use of strong CYP3A4 inhibitors that prolong the QTc interval is contraindicated in patients undergoing therapy with pacritinib.(1) Consider alternatives with no or minimal enzyme inhibition and with no effect on the QTc interval. If coadministration is unavoidable, monitor for prolongation of the QTc interval.(1) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(1)

DISCUSSION: Clarithromycin (500 mg twice daily for 5 days) increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(1) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(5) Strong inhibitors of CYP3A4 that prolong QT include: adagrasib, ceritinib, clarithromycin, levoketoconazole, lopinavir, posaconazole, ribociclib, saquinavir, telithromycin, and voriconazole.(3,4)

Selected Moderate Cyp3a4 Inducers/Ensartinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of ensartinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may reduce the clinical effectiveness of ensartinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of ensartinib states that concurrent use of moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: Ensartinib is predominately metabolized by CYP3A4.(1) Moderate CYP3A4 inducers linked to this monograph are: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pexidartinib, pacritinib, repotrectinib, rifabutin, telotristat, thioridazine, and tovorafenib.(2,3)

Slt Moderate And Strong Cyp3a4 Inducers/Ixazomib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Ixazomib is primarily metabolized by CYP3A4.(1)

CLINICAL EFFECTS: Concurrent use of strong or selected moderate CYP3A4 inducers will result in decreased systemic concentrations of ixazomib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of ixazomib states that concomitant use with CYP3A4 inducers should be avoided. In an interaction study, rifampin decreased ixazomib exposure(AUC) by 74%.(1) Use an alternative to the inducing agent when possible. The onset of induction is gradual but may begin within one week for potent agents (e.g. rifampin). The time to maximal induction may be 2 or more weeks depending upon the half-life and dose of the inducer.

DISCUSSION: In an interaction study, coadministration with rifampin decreased ixazomib AUC 74% and maximum concentration (Cmax) by 54%(1) Selected moderate and strong CYP3A4 inducers linked to this monograph are: apalutamide, barbiturates, belzutifan, carbamazepine, cenobamate, dabrafenib, elagolix, encorafenib, enzalutamide, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's Wort, sotorasib, telotristat, and tovorafenib.(2)

Slt Moderate-Strong Cyp3a4 Inducers/Slt Hepatitis C Agents

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong or moderate inducers of CYP3A4 may induce the metabolism of asunaprevir or ombitasvir-paritaprevir-ritonavir treatment for hepatitis C.(1-3) Asunaprevir is also a substrate for the OATP1B1 transporter. OATP1B1 facilitated transport into the liver is thought to be associated with asunaprevir efficacy. While rifampin a strong CYP3A4 inducer, is also an OATP1B1 inhibitor and so may further decrease asunaprevir efficacy by inhibiting its transport into the liver.

CLINICAL EFFECTS: The combination of asunaprevir or ombitasvir-paritaprevir-ritonavir, with or without dasabuvir, may not be effective for the treatment of hepatitis C.(1-3)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Because of the risk for treatment failure, the manufacturers of asunaprevir, and ombitasvir-paritaprevir-ritonavir state that concomitant use with strong or moderate CYP3A4 inducers is contraindicated.(1-3)

DISCUSSION: In an interaction study with 12 subjects, carbamazepine 200 mg once daily followed by 200 mg twice daily decreased antiviral exposure (area-under-curve or AUC) of ombitasvir by 31%, paritaprevir by 70%, ritonavir by 87%, and dasabuvir by 55%.(1) Strong and moderate CYP3A4 inducers linked to this monograph are: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifapentine, sotorasib, telotristat, and tovorafenib.

Strong & Mod Cyp3a4 Inducers That Prolong Qt/Bedaquiline

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers that prolong the QTc interval may induce the metabolism of bedaquiline and result in additive risk of QT prolongation.(1,2)

CLINICAL EFFECTS: Concurrent or recent use of strong or moderate CYP3A4 inducers that prolong the QTc interval may result in decreased levels and effectiveness of bedaquiline and may cause additive effects on the QTc interval, which may result in life-threatening cardiac arrhythmias including torsades de pointes.(1,2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The concurrent administration of strong or moderate CYP3A4 inducers and bedaquiline should be avoided.(1) Bedaquiline should be used with caution in patients receiving therapy with agents that prolong the QT interval. Patients should receive a baseline electrocardiogram (ECG) before initiation, 2 weeks after initiation, during treatment as clinically indicated, and at the expected time of maximum increase of the QT interval when receiving concurrent agents that prolong the QT interval. Bedaquiline and other QT prolonging agents should be discontinued if the patient develops a clinically significant ventricular arrhythmia or a QTcF of greater than 500 msec confirmed by repeat ECGs. If a patient develops syncope, perform an ECG.(1) Also consider obtaining serum calcium, magnesium, and potassium levels at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a study in healthy subjects, concurrent administration of rifampin (600 mg daily) and bedaquiline (300 mg daily) for 21 days decreased the area-under-curve (AUC) of bedaquiline by 52%.(1) In a study in healthy subjects, pretreatment with efavirenz (600 mg daily for 27 days) decreased the AUC of a single dose of bedaquiline by 20%. There was no effect on bedaquiline Cmax. The AUC and Cmax of the primary metabolite of bedaquiline increased by 70% and 80%, respectively.(1) In a clinical trial, mean increases in QTc were greater in patients treated with bedaquiline than with placebo. At Week 1, bedaquiline increased QTc by an average of 9.9 msec, compared with 2.5 msec for placebo. At Week 24, bedaquiline increased QTc by an average of 15.7 msec, compared with 6.2 msec for placebo. In another clinical trial in which patients received bedaquiline with other QT prolonging agents, QT prolongation was additive and proportional to the number of QT prolonging drugs used. Patients receiving bedaquiline alone averaged a QTc increase of 23.7 msec over baseline, while patients receiving bedaquiline with at least one other QT prolonging agent averaged a QTc increase of 30.7 msec.(1) In a study, bedaquiline was coadministered with QTc prolonging agents clofazimine and levofloxacin. In the study, 5% of patients had a QTc >= 500 ms and 43% of patients had an increase in QTc >= 60 ms from baseline.(1) Strong and moderate inducers of CYP3A4 that prolong QT include: efavirenz, encorafenib, fexinidazole, ivosidenib, pacritinib, and thioridazine.(3,4)

Strong & Moderate 3A4 Inducers That Prolong Qt/Fexinidazole

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate inducers of CYP3A4 that prolong the QTc interval may increase the metabolism of fexinidazole to its active metabolites and result in increased systemic exposure and increased risk for adverse reactions, including additive risk of QT prolongation.(1)

CLINICAL EFFECTS: Concurrent use of a strong or moderate CYP3A4 inducers that prolongs QT may result in increased levels of fexinidazole's active metabolites (M1 and M2), which may lead to increased risk of adverse reactions.(1) Concurrent use may cause additive effects on the QTc interval, which may result in life-threatening cardiac arrhythmias including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of fexinidazole with medications that prolong the QT interval and induce CYP3A4.(1) Avoid use of fexinidazole in patients who have a baseline QTcF interval greater than 470 msec, a history of torsades de pointes, congenital long QT syndrome, cardiac arrhythmias, uncompensated heart failure, or family history of sudden death, or uncorrected hypokalemia.(1) If patients are, or need to be, treated with drugs known to prolong the QTcF interval or to induce bradycardia, do not initiate therapy with fexinidazole until such drugs are eliminated from the body (allow a washout period of 5 half-lives for such other drugs). Do not start such drugs until fexinidazole therapy is eliminated (allow a washout period of 7 days).(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Fexinidazole is metabolized to its active metabolites, M1 and M2, by CYP3A4. M2 plasma concentrations have been associated with the increased risk of QT prolongation.(1) In clinical studies, fexinidazole was associated with a concentration-dependent QTcF prolongation. At recommended therapeutic doses, the mean (upper 90% confidence interval) increase in QTcF is predicted to be 19.0 msec (23.3 msec). The observed increase in QTcF appears to be associated with the M2 (sulfone) metabolite of fexinidazole.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) Strong and moderate inducers of CYP3A4 that prolong QT include: efavirenz, encorafenib, ivosidenib, pacritinib, and thioridazine.(3)

Strong & Moderate Cyp3a4 Inducer That Prolong Qt/Quizartinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong or moderate inducers of CYP3A4 that prolong the QTc interval may accelerate the metabolism of quizartinib.(1) Quizartinib prolongs the QTc interval.(1) Some CYP3A4 inducers (e.g., efavirenz, thioridazine) can also prolong the QTc interval.(3,4)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers may decrease the levels and effectiveness of quizartinib.(1) Additive QTc prolongation may occur and result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of quizartinib states that the concurrent use of QT prolonging agents should be avoided.(1) Avoid the concurrent use of strong or moderate CYP3A4 inducers in patients receiving therapy with quizartinib.(1) Quizartinib is only available through a restricted REMS program due to the serious risk of QT prolongation, torsades de pointes, and cardiac arrest. The manufacturer recommends monitoring as follows: -Initiate quizartinib only if the QTcF is less than or equal to 450 ms. -During induction and consolidation, monitor ECGs prior to initiation and then at minimum once weekly during treatment. -During maintenance, monitor ECGs prior to initiation and then at minimum once weekly for the first month following dose initiation and escalation and clinically therafter. Dose escalation may occur only if the QTcF is less than or equal to 450 ms. The manufacturer recommends the following dose modifications for adverse reactions: -If the QTcF is 450 ms to 480 ms (Grade 1) - Continue quizartinib dose. -If the QTcF is 481 ms to 500 ms (Grade 2) - Reduce the dose of quizartinib without interruption based on prescribing information. Resume the previous dose in the next cycle if the QTcF has decreased to less than 450 ms. -If the QTcF is greater than 500 ms (Grade 3) - Interrupt quizartinib. Resume at a reduced dose based on prescribing information when the QTcF is less than 450 ms. Maintain the dose of 26.5 mg once daily during maintenance if the QTcF is greater than 500 ms during induction or consolidation. -If recurrent QTcF is greater than 500 ms (Grade 3) - Permanently discontinue quizartinib if QTcF is greater than 500 ms despite dose reduction and correction/elimination of other risk factors. -If TdP, polymorphic ventricular tachycardia, or signs/symptoms of life-threatening arrhythmia occur (Grade 4) - Permanently discontinue quizartinib. When concurrent therapy cannot be avoided, obtain ECGs and electrolyte values (serum calcium, magnesium, and potassium) prior to the start of treatment, after initiation of any drug known to prolong the QT interval, and periodically monitor during therapy. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: The area-under-curve (AUC) of quizartinib decreased by 90% and maximum concentration (Cmax) by 45% following concomitant use of a single 53 mg dose of quizartinib with efavirenz (a moderate CYP3A inducer). The AUC of active metabolite AC886 decreased by 96% and the Cmax by 68%. The effect of concomitant use with a strong CYP3A inducer may result in even greater effect on quizartinib pharmacokinetics based on mechanistic understanding of the drugs involved.(1) Quizartinib has been associated with QTc interval prolongation, Torsades de Pointes, ventricular arrhythmias, cardiac arrest, and sudden death. Quizartinib increased QTc in a dose- and concentration-dependent manner.(1) In an exposure-response analysis, quizartinib had a predicted concentration-dependent QTc prolongation of 18 to 24 ms (upper bound of 2-sided 90% CI: 21 and 27 ms) at a median steady-state Cmax dose of 26.5 mg and 53 mg during maintenance therapy.(1) In patients administered quizartinib, 2.3% of 265 patients had a QTcF greater than 500 msec and 10% of patients had a increase from baseline QTcF greater than 60 msec.(1) In patients administered quizartinib during the induction phase, torsades de pointes occurred in approximately 0.2% of patients, cardiac arrest occurred in 0.6%, including 0.4% with a fatal outcome, and 0.1% of patients experienced ventricular fibrillation.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2) Strong inducers of CYP3A4 include: encorafenib and ivosidenib. Moderate inducers of CYP3A4 include: efavirenz, fexinidazole, pacritinib, and thioridazine.(3,4)

Strong & Moderate Cyp3a4 Inducers/Axitinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Agents that induce the CYP3A4 isoenzyme may induce the metabolism of axitinib.(1)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers may decrease the levels and effectiveness of axitinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of strong or moderate CYP3A4 inducers in patients receiving therapy with axitinib.(1) Consider the use of alternatives with little to no induction potential.(1)

DISCUSSION: Rifampin (600 mg daily for 9 days), a strong CYP3A4 inducer, decreased the maximum concentration (Cmax) and area-under-curve (AUC) of axitinib to less than half and less than 25% of levels seen without concurrent rifampin.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, dexamethasone, encorafenib, enzalutamide, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifabutin, rifampin, rifapentine, and St. John's wort. Moderate inducers of CYP3A4 include: bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat ethyl, thioridazine and tovorafenib.(1-3)

Strong & Moderate Cyp3a4 Inducers/Cobimetinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Agents that induce the CYP3A4 isoenzyme may induce the metabolism of cobimetinib.(1)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers may decrease the levels and effectiveness of cobimetinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of strong or moderate CYP3A4 inducers in patients receiving therapy with cobimetinib.(1) Consider the use of alternatives with little to no induction potential.

DISCUSSION: Based upon simulations, coadministration of cobimetinib with a strong CYP3A4 inducer may decrease cobimetinib exposure by 83%, with a moderate CYP3A4 inducer by 73%, leading to a reduction in efficacy.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, cenobamate, encorafenib, enzalutamide, ivosidenib, lorlatinib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifabutin, rifampin, rifapentine, and St. John's wort. Moderate inducers of CYP3A4 include: bosentan, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(1-3)

Strong & Moderate Cyp3a4 Inducers/Sonidegib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Agents that induce the CYP3A4 isoenzyme may induce the metabolism of sonidegib.(1)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers may decrease the levels and effectiveness of sonidegib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of strong or moderate CYP3A4 inducers in patients receiving therapy with sonidegib.(1) Consider the use of alternatives with little to no induction potential.

DISCUSSION: In an interaction study, 16 healthy subjects received a single dose of sonidegib 800mg alone or 5 days after receiving rifampin 600 mg daily for 14 days. Mean sonidegib area-under-curve (AUC) was decreased by 75% and maximum concentration (Cmax) decreased 54% when taken with rifampin. Based upon population based pharmacokinetic (PBPK) simulations, a moderate CYP3A4 inducer such as efavirenz given for 14 days is predicted to decrease sonidegib AUC 56% in cancer patients taking sonidegib 200 mg daily. Coadministration with a moderate CYP3A4 inducer for 4 months is predicted to decrease sonidegib exposure (AUC) by 69%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort. Moderate inducers of CYP3A4 include: bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2-3)

Strong And Mod Cyp3a4 Inducers That Prolong Qt/Glasdegib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Glasdegib is a substrate of CYP3A4. Strong and moderate inducers of CYP3A4 that prolong the QTc interval may induce the metabolism of glasdegib and result in additive risk of QT prolongation.(1)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 that prolongs QT may result in decreased levels and effectiveness of glasdegib and may cause additive effects on the QTc interval, which may result in life-threatening cardiac arrhythmias including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of glasdegib states to avoid concurrent administration with strong or moderate CYP3A4 inducers. If concurrent use with a moderate CYP3A4 inducer cannot be avoided, increase the daily dose of glasdegib as tolerated as follows: - If current dose of glasdegib is 100 mg once daily, increase to 200 mg once daily - If current dose of glasdegib is 50 mg once daily, increase to 100 mg once daily After the moderate CYP3A4 inducer has been discontinued for 7 days, resume the glasdegib dose that was tolerated prior to initiation of the inducer.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.(2)

DISCUSSION: A population-based pharmacokinetic model predicts that efavirenz would decrease glasdegib area-under-curve (AUC) by 55% and maximum concentration (Cmax) by 25%.(1) Strong and moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, encorafenib, fexinidazole, ivosidenib, pacritinib, and thioridazine.(3,4)

Strong And Mod Cyp3a4 Inducers That Prolong Qt/Pimavanserin

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong or moderate inducers of CYP3A4 that prolong the QTc interval may induce the metabolism of pimavanserin and result in additive risk of QT prolongation.(1,2)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 that prolongs the QTc interval may result in decreased levels and effectiveness of pimavanserin and may cause additive effects on the QTc interval, which may result in life-threatening cardiac arrhythmias including torsades de pointes.(1,2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of pimavanserin recommends avoiding concomitant use of strong or moderate CYP3A4 inducers.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Pimavanserin is primarily metabolized by CYP3A4 while other metabolic enzymes CYP2J2, CYP2D6 and FMO play a lesser role.(1) In a study of subjects pretreated with 7 days of rifampin (600 mg daily, a strong CYP3A4 inducer), a single dose of pimavanserin (34 mg) produced an area-under-curve (AUC) and maximum concentration (Cmax) that was 91 % and 71 % lower, respectively, than when pimavanserin is given without rifampin.(1) A physiology-based pharmacokinetic model predicted that efavirenz (a moderate CYP3A4 inducer) would decrease pimavanserin AUC and Cmax by 70 % and 60 %, respectively.(1) Strong and moderate inducers of CYP3A4 that prolong QT include: efavirenz, encorafenib, fexinidazole, ivosidenib, pacritinib, and thioridazine.(4,5)

Strong And Mod Cyp3a4 Inducers That Prolong Qt/Selpercatinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of selpercatinib.(1) Selpercatinib prolongs the QTc interval.(1) Some CYP3A4 inducers (e.g., efavirenz, encorafenib, ivosidenib, thioridazine) can also prolong the QTc interval.(2)

CLINICAL EFFECTS: Coadministration of selpercatinib with a strong or moderate CYP3A4 inducer decreases selpercatinib plasma concentrations, which may decrease the efficacy of selpercatinib.(1) It is unknown how decreased levels of selpercatinib affects the risk of QTc interval prolongation when selpercatinib is used concurrently with QT prolonging CYP3A4 inducers. The concurrent use of selpercatinib with other QT prolonging agents may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1,2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of selpercatinib states that concurrent use with strong and moderate CYP3A4 inducers should be avoided.(1) When concurrent therapy with QT prolonging CYP3A4 inducers is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.(3)

DISCUSSION: In a study, multiple doses of rifampin (a strong CYP3A inducer) decreased the area-under-curve (AUC) and maximum concentration (Cmax) of selpercatinib by 87% and 70%, respectively.(1) Coadministration of multiple doses of bosentan or efavirenz (moderate CYP3A inducers) is predicted to decrease the AUC and Cmax of selpercatinib 40-70% and 34-57%, respectively.(1) Strong and moderate CYP3A4 inducers that prolong QT include: efavirenz, encorafenib, fexinidazole, ivosidenib, pacritinib, and thioridazine.(4,5)

Strong And Moderate Cyp3a4 Inducers/Capivasertib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate inducers of CYP3A4 may increase the metabolism of capivasertib.(1)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 may result in decreased levels and effectiveness of capivasertib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of capivasertib with strong and moderate CYP3A4 inducers.(1)

DISCUSSION: Rifampin (strong CYP3A4 inducer) is predicted to decrease capivasertib area-under-curve (AUC) by 70% and maximum concentration (Cmax) by 60%.(1) Efavirenz (moderate CYP3A4 inducer) is predicted to decrease capivasertib AUC by 60% and Cmax by 50%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, and tovorafenib.(2,3)

Strong And Moderate Cyp3a4 Inducers/Capmatinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of capmatinib by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong and moderate CYP3A4 inducers and capmatinib may result in decreased exposure to capmatinib and decreased anti-tumor activity.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of strong and moderate CYP3A4 inducers with capmatinib.(1)

DISCUSSION: Coadministration with rifampin (a strong CYP3A4 inducer) decreased capmatinib area-under-curve (AUC) by 67% and maximum concentration (Cmax) by 56%. Coadministration with efavirenz (a moderate CYP3A4 inducer) was predicted to decrease capmatinib AUC by 44% and Cmax by 34%.(1) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(2)

Strong And Moderate Cyp3a4 Inducers/Elacestrant

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Elacestrant is metabolized by CYP3A4. Strong and moderate inducers of CYP3A4 may increase the metabolism of elacestrant.(1)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 may result in decreased levels and effectiveness of elacestrant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of elacestrant states avoid concomitant use of elacestrant with strong or moderate CYP3A4 inducers.(1) The US manufacturer of elacestrant does not provide dose modification recommendations with strong and moderate CYP3A4 inducers. The Australian and UK manufacturers of elacestrant state concomitant use of strong or moderate CYP3A4 inducers should be avoided and an alternative concomitant medicinal product with no or minimal potential to induce CYP3A4 should be considered. If a strong or moderate CYP3A4 inducer must be used for a short duration of time (i.e. less than or equal to 3 days) or intermittently (i.e. treatment periods less than or equal to 3 days separated by at least 2 weeks or 1 week + 5 half-lives of the CYP3A4 inducer, whichever is longer), continue elacestrant without increasing the dose.(2,3)

DISCUSSION: Coadministration of 200 mg dose of elacestrant with rifampin (a strong CYP3A inducer) decreased the maximum concentration (Cmax) and area-under-curve (AUC) of elacestrant by 73% and 86%, respectively.(1) Efavirenz is predicted to decrease the Cmax and AUC of elacestrant by 44 to 63% and 55% to 73%, respectively.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(4,5) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(4,5)

Strong And Moderate Cyp3a4 Inducers/Finerenone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of finerenone by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong or moderate CYP3A4 inducers with finerenone may result in decreased levels and clinical effectiveness of finerenone.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of strong or moderate CYP3A4 inducers with finerenone.(1)

DISCUSSION: Finerenone is a substrate of CYP3A4. Concurrent use of efavirenz (a moderate CYP3A4 inducer) and rifampicin (a strong CYP3A4 inducer) decreased finerenone area-under-curve (AUC) by 80% and 90%, respectively.(1) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(2,3)

Strong And Moderate Cyp3a4 Inducers/Ibrexafungerp

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of ibrexafungerp by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong or moderate CYP3A4 inducers with ibrexafungerp may result in decreased levels and clinical effectiveness of ibrexafungerp.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of strong and moderate CYP3A4 inducers with ibrexafungerp.(1)

DISCUSSION: Ibrexafungerp is a substrate of CYP3A4. The manufacturer of ibrexafungerp states that concurrent use of strong or moderate CYP3A4 inducers are likely to significantly reduce ibrexafungerp exposure, but this interaction has not been studied.(1) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(2,3)

Strong And Moderate Cyp3a4 Inducers/Infigratinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of infigratinib by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong and moderate CYP3A4 inducers and infigratinib may result in decreased levels and clinical effectiveness of infigratinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of strong and moderate CYP3A4 inducers with infigratinib.(1)

DISCUSSION: Coadministration of multiple doses of rifampin (a strong CYP3A4 inducer) decreased infigratinib area-under-curve (AUC) and maximum concentration (Cmax) by 56% and 44%, respectively.(1) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(3)

Strong And Moderate Cyp3a4 Inducers/Lemborexant

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Lemborexant is a substrate of CYP3A4. Strong or moderate inducers of CYP3A4 may induce the metabolism of lemborexant.(1)

CLINICAL EFFECTS: The concurrent administration of strong or moderate CYP3A4 inducers may result in decreased levels and effectiveness of lemborexant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of lemborexant states that concurrent use with strong or moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: A pharmacokinetic model predicted that co-administration of rifampin, a strong CYP3A4 inducer, would decrease the AUC of lemborexant by 90%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort. Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Strong And Moderate Cyp3a4 Inducers/Leniolisib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Leniolisib is metabolized by CYP3A4. Strong and moderate inducers of CYP3A4 may increase the metabolism of leniolisib.(1)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 may result in decreased levels and effectiveness of leniolisib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of leniolisib with strong or moderate CYP3A4 inducers.(1)

DISCUSSION: PBPK model-based simulations predicted a maximum decrease of 78% and 58% in leniolisib area-under-curve (AUC) with rifampin (strong CYP3A4 inducer) and efavirenz (moderate CYP3A4 inducer), respectively.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(2,3)

Strong And Moderate Cyp3a4 Inducers/Neratinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inducers of CYP3A4 may induce the metabolism of neratinib.(1)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers may result in decreased effectiveness of neratinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of neratinib with strong or moderate inducers of CYP3A4.(1) If concurrent use is warranted, monitor patients closely for decreased neratinib effectiveness.

DISCUSSION: Rifampin, a strong CYP3A4 inducer, decreased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of neratinib (240 mg) by 76% and 87%, respectively.(1) Strong CYP3A4 inducers include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifabutin, rifampin, rifapentine and St. John's wort.(1,2) Moderate CYP3A4 inducers include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat, thioridazine, and tovorafenib.(1,2)

Strong And Moderate Cyp3a4 Inducers/Nirogacestat

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong or moderate CYP3A4 inducers may induce the metabolism of nirogacestat.(1)

CLINICAL EFFECTS: Coadministration of nirogacestat with a strong or moderate CYP3A4 inducer decreases nirogacestat plasma concentrations, which may decrease efficacy of nirogacestat.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of nirogacestat states that concurrent use with strong or moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: In a PKPB model, coadministration of rifampin, a strong CYP3A4 inducer, following multiple doses of nirogacestat (150 mg BID) is predicted to decrease the area-under-curve (AUC) of nirogacestat by 85%.(1) In a PKPB model, coadministration of efavirenz, a moderate CYP3A4 inducer, following multiple doses of nirogacestat (150 mg BID) is predicted to decrease the AUC of nirogacestat by 67%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, modafinil, nafcillin, pacritinib, pexidartinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Strong And Moderate Cyp3a4 Inducers/Olutasidenib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of olutasidenib by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong and moderate CYP3A4 inducers and olutasidenib may result in decreased levels and clinical effectiveness of olutasidenib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of strong and moderate CYP3A4 inducers with olutasidenib.(1)

DISCUSSION: Coadministration of multiple doses of rifampin (a strong CYP3A4 inducer) decreased olutasidenib area-under-curve (AUC) and maximum concentration (Cmax) by 80% and 43%, respectively.(1) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(2)

Strong And Moderate Cyp3a4 Inducers/Omaveloxolone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Omaveloxolone is metabolized by CYP3A4. Strong and moderate inducers of CYP3A4 may increase the metabolism of omaveloxolone.(1)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 may result in decreased levels and effectiveness of omaveloxolone.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of omaveloxolone with strong or moderate CYP3A4 inducers.(1)

DISCUSSION: Omaveloxolone is a substrate of CYP3A4. The effect of concomitant use with strong CYP3A4 inducers is unknown. Concurrent administration of a single dose of efavirenz (moderate CYP3A4 inducer) with omaveloxolone decreased the maximum concentration (Cmax) and area-under-the-curve (AUC) of omaveloxolone by 38% and 48%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(2,3)

Strong And Moderate Cyp3a4 Inducers/Palovarotene

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Palovarotene is extensively metabolized by CYP3A4. Strong and moderate inducers of CYP3A4 may increase the metabolism of palovarotene.(1)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 may result in decreased levels and effectiveness of palovarotene.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of palovarotene with strong and moderate CYP3A4 inducers.(1)

DISCUSSION: In a clinical trial, rifampin, a strong CYP3A4 inducer, decreased the maximum concentration (Cmax) and area-under-curve (AUC) of palovarotene by 81% and 89%, respectively.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2)

Strong And Moderate Cyp3a4 Inducers/Pemigatinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of pemigatinib by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong and moderate CYP3A4 inducers and pemigatinib may result in decreased levels and clinical effectiveness of pemigatinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of strong and moderate CYP3A4 inducers with pemigatinib.(1)

DISCUSSION: Rifampin, a strong CYP3A4 inducer, decreased pemigatinib maximum concentration (Cmax) by 62% and area-under-curve (AUC) by 85% following a single pemigatinib oral dose of 13.5 mg. Concomitant use of a moderate CYP3A4 inducer is predicted to decrease pemigatinib exposure by more than 50%. Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, mavacamten, lumacaftor, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(3)

Strong And Moderate Cyp3a4 Inducers/Rimegepant

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of rimegepant by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong and moderate CYP3A4 inducers and rimegepant may result in decreased levels and clinical effectiveness of rimegepant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of rimegepant recommends avoiding concurrent use with strong or moderate CYP3A4 inducers due to potential decrease in exposure to rimegepant and loss of efficacy.(1) Patients receiving concurrent therapy with strong and moderate CYP3A4 inducers and rimegepant should be observed for decreased clinical effectiveness.

DISCUSSION: In a drug interaction study, rifampin, a strong CYP3A4 inducer, decreased the area-under-curve (AUC) and maximum concentration (Cmax) of rimegepant (75 mg) by 80% and 64%, respectively.(1) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(1,2)

Strong And Moderate Cyp3a4 Inducers/Selumetinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of selumetinib by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong and moderate CYP3A4 inducers and selumetinib may result in decreased levels and clinical effectiveness of selumetinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of selumetinib recommends avoiding concurrent use with strong or moderate CYP3A4 inducers due to potential decrease in exposure to selumetinib and loss of efficacy.(1) Patients receiving concurrent therapy with strong and moderate CYP3A4 inducers and selumetinib should be observed for decreased clinical effectiveness.

DISCUSSION: In a study of 22 healthy subjects, rifampin 600 mg daily (a strong CYP3A4 inducer) decreased selumetinib area-under-curve (AUC) and maximum concentration (Cmax) by 51% and 26%, respectively.(2) Concomitant use of efavirenz, a moderate CYP3A4 inducer, is predicted to decrease selumetinib AUC and Cmax by 38% and 22%, respectively.(1) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(3)

Strong And Moderate Cyp3a4 Inducers/Voclosporin

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the metabolism of voclosporin.(1)

CLINICAL EFFECTS: Concurrent use of strong and moderate CYP3A4 inducers may decrease the serum levels and effectiveness of voclosporin.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The use of strong or moderate CYP3A4 inducers with voclosporin should be avoided.(1)

DISCUSSION: Concurrent use of voclosporin with rifampin 600 mg daily for 10 days (strong CYP3A4 inducer) decreased the concentration maximum (Cmax) and area-under-curve (AUC) by 0.32-fold and 0.13-fold, respectively.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Strong Or Moderate 3A4 Inducers That Prolong Qt/Mobocertinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong or moderate inducers of CYP3A4 that prolong the QTc interval may accelerate the metabolism of mobocertinib.(1) Mobocertinib prolongs the QTc interval.(1) Some CYP3A4 inducers (e.g., efavirenz, ivosidenib, thioridazine) can also prolong the QTc interval.(2)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers that prolong the QTc interval may result in a loss of mobocertinib efficacy. Additive QTc prolongation may occur and result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the use of strong or moderate CYP3A4 inducers that prolong QT in patients undergoing therapy with mobocertinib.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Increase the frequency of ECG monitoring in patients with risk factors for QTc prolongation, including congenital long QT syndrome, heart disease, or electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation during mobocertinib therapy, dose modifications are recommended: - If Grade 2 (QTc interval 481-500 msec) and first occurrence: hold mobocertinib until QTc returns to <= Grade 1 or baseline. Upon recovery, resume mobocertinib at the same dose. - If Grade 2 and recurrence: hold mobocertinib until QTc returns to <= Grade 1 or baseline. Upon recovery, resume mobocertinib at the next lower dose or permanently discontinue. - If Grade 3 (QTc interval >= 501 msec or QTc interval increase of > 60 msec from baseline) and first occurrence: hold mobocertinib until QTc returns to <= Grade 1 or baseline. Upon recovery, resume mobocertinib at the next lower dose or permanently discontinue. - If Grade 3 and recurrence: permanently discontinue mobocertinib. - If Grade 4 (Torsades de pointes; polymorphic ventricular tachycardia; signs/symptoms of serious arrhythmia): permanently discontinue mobocertinib.

DISCUSSION: Coadministration of mobocertinib with multiple doses of rifampin (a strong CYP3A inducer) is predicted to decrease the steady-state combined molar area-under-curve (AUC) of mobocertinib and its active metabolites by 92%.(1) Coadministration of mobocertinib with multiple doses of efavirenz (a moderate CYP3A inducer) is predicted to decrease the steady-state combined molar AUC of mobocertinib and its active metabolites by 58%.(1) In a clinical study, mobocertinib 160 mg once daily was associated with a concentration-dependent increase in QTc, with the largest mean increase in QTc of 23 msec.(1) In clinical studies, patients were excluded if baseline QTc was greater than 470 msec. In a subset of 250 patient with scheduled and unscheduled electrocardiograms (ECGs), 1.2% of patients had a QTc interval >500 msec and 11% of patients had a change-from-baseline QTc interval >60 msec. Grade 4 Torsades de Pointes occurred in 1 patient (0.4%).(1) Strong inducers of CYP3A4 that prolong the QTc interval include: encorafenib and ivosidenib. Moderate inducers of CYP3A4 that prolong the QTc interval include: efavirenz, fexinidazole, pacritinib, and thioridazine.(4,5)

Strong Or Moderate Cyp3a4 Inducers/Avapritinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong or moderate CYP3A4 inducers may induce the metabolism of avapritinib.

CLINICAL EFFECTS: Coadministration of avapritinib with a strong or moderate CYP3A4 inducer decreases avapritinib plasma concentrations, which may decrease efficacy of avapritinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of avapritinib states that concurrent use with strong or moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: Coadministration of avapritinib 400 mg as a single dose with rifampin 600 mg daily, a strong CYP3A4 inducer, decreased avapritinib concentration maximum (Cmax) by 74% and area-under-curve (AUC) by 92%.(1) Coadministration of avapritinib 300 mg once daily with efavirenz 600 mg once daily, a moderate CYP3A4 inducer, is predicted to decrease avapritinib Cmax by 55% and AUC by 62% at steady state.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine and tovorafenib.(2,3)

Strong Or Moderate Cyp3a4 Inducers/Daridorexant

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Daridorexant is a substrate of CYP3A4. Strong or moderate inducers of CYP3A4 may induce the metabolism of daridorexant.(1)

CLINICAL EFFECTS: The concurrent administration of strong or moderate CYP3A4 inducers may result in decreased levels and effectiveness of daridorexant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of daridorexant states that concurrent use with strong or moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: Concomitant use of rifampin, a strong CYP3A4 inducer, with daridorexant 50 mg decreased daridorexant area-under-curve (AUC) by more than 50%. Efavirenz 600 mg, a moderate CYP3A4 inducer, decreased daridorexant AUC and maximum concentration (Cmax) by 60% and 40%, respectively.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort. Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Strong Or Moderate Cyp3a4 Inducers/Repotrectinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong or moderate CYP3A4 inducers may induce the metabolism of repotrectinib.(1)

CLINICAL EFFECTS: Coadministration of repotrectinib with a strong or moderate CYP3A4 inducer decreases repotrectinib plasma concentrations, which may decrease efficacy of repotrectinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of repotrectinib states that concurrent use with strong or moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: Coadministration of repotrectinib with rifampin, a strong CYP3A4 and P-glycoprotein inducer, decreased concentration maximum (Cmax) by 79% and area-under-curve (AUC) by 92%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, encorafenib, etravirine, lesinurad, modafinil, nafcillin, pacritinib, pexidartinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Strong Or Moderate Cyp3a4 Inducers/Tazemetostat

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Strong or moderate CYP3A4 inducers may induce the metabolism of tazemetostat.(1)

CLINICAL EFFECTS: Coadministration of tazemetostat with a strong or moderate CYP3A4 inducer may decrease tazemetostat plasma concentrations, which may decrease the efficacy of tazemetostat.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of tazemetostat says to avoid coadministration of strong or moderate CYP3A4 inducers with tazemetostat.(1)

DISCUSSION: Tazemetostat is a known substrate of CYP3A4. According to the manufacturer, coadministration with a strong or moderate CYP3A4 inducer may decrease tazemetostat plasma concentrations which may decrease the efficacy of tazemetostat. No clinical studies have been conducted.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(2,3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Strong Or Moderate Cyp3a4 Inducers/Vonoprazan

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Vonoprazan is a substrate of CYP3A4. Strong or moderate inducers of CYP3A4 may increase the metabolism of vonoprazan.(1)

CLINICAL EFFECTS: The concurrent administration of strong or moderate CYP3A4 inducers may result in decreased levels and effectiveness of vonoprazan.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of vonoprazan states that concurrent use with strong or moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: Strong CYP3A4 inducers like rifampin are predicted to decrease the area-under-curve (AUC) of vonoprazan by 80%, and moderate CYP3A4 inducers like efavirenz are predicted to decrease vonoprazan AUC by 50%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort. Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2-3)

Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

Cyp3a4 Inducers/Erlotinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Inducers of CYP3A4 may induce the metabolism of erlotinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a CYP3A4 inducer may result in decreased levels and effectiveness of erlotinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of CYP3A4 inducers in patients receiving therapy with erlotinib. Consider the use of alternative agents with less enzyme induction potential.(1) Consider increasing the dosage of erlotinib by 50 mg increments as tolerated at two week intervals (to a maximum of 450 mg) while closely monitoring the patient. The highest dosage studied with concurrent rifampin is 450 mg. If the dosage of erlotinib is increased, it will need to be decreased when the inducer is discontinued.(1)

DISCUSSION: Pretreatment and concurrent therapy with rifampin increased erlotinib clearance by 3-fold and decreased the erlotinib area-under-curve (AUC) by 66% to 80%. This is equivalent to a dose of about 30 mg to 50 mg in NSCLC.(1) In a study, pretreatment with rifampin for 11 days decreased the AUC of a single 450 mg dose of erlotinib to 57.6% of the AUC observed with a single 150 mg dose of erlotinib.(1) In a case report, coadministration of phenytoin (180mg daily) and erlotinib (150mg daily) increased the phenytoin concentration from 8.2mcg/ml to 24.2mcg/ml and decreased the erlotinib concentration 12-fold (from 1.77mcg/ml to 0.15mcg/ml) and increased the erlotinib clearance by 10-fold (from 3.53 L/h to 41.7 L/h).(2) In a study, concurrent use of sorafenib (400 mg twice daily) and erlotinib (150 mg daily) decreased the concentration minimum (Cmin), concentration maximum (Cmax), and AUC of erlotinib.(3) In an animal study, concurrent use of dexamethasone and erlotinib decreased the AUC of erlotinib by 0.6-fold.(4) Strong inducers of CYP3A4 include: barbiturates, encorafenib, enzalutamide, fosphenytoin, ivosidenib, mitotane, phenobarbital, phenytoin, primidone, rifampin, and rifapentine.(5,6) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat, thioridazine, and tovorafenib.(5,6) Weak inducers of CYP3A4 include: amprenavir, armodafinil, aumolertinib, bexarotene, brigatinib, brivaracetam, clobazam, danshen, darolutamide, dicloxacillin, echinacea, eslicarbazepine, flucloxacillin, garlic, genistein, ginkgo, ginseng, glycyrrhizin, mobocertinib, nevirapine, omaveloxolone, oritavancin, oxcarbazepine, pioglitazone, pitolisant, quercetin, relugolix, rufinamide, sarilumab, sulfinpyrazone, sunvozertinib, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vemurafenib, vinblastine, and zanubrutinib.(5,6)

Moderate Cyp3a4 Inducer/Vanzacaftor-Tezacaftor-Deutivacaftor

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of vanzacaftor, tezacaftor, and deutivacaftor.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of vanzacaftor, tezacaftor, and deutivacaftor.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Concurrent use of moderate CYP3A4 inducers in patients maintained on vanzacaftor-tezacaftor-deutivacaftor is not recommended.(1)

DISCUSSION: Concurrent administration with efavirenz (a moderate inducer of CYP3A4) is predicted to decrease vanzacaftor and deutivacaftor area-under-curve (AUC) by 69% and 73%, respectively, and maximum concentration (Cmax) by 65% and 56%, respectively.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers That Prolong Qt/Aumolertinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Aumolertinib is a CYP3A4 substrate and has been shown to prolong the QTc interval. Moderate CYP3A4 inducers may induce the metabolism of aumolertinib.(1) Concurrent use of agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers that prolong QT may result in decreased levels and effectiveness of aumolertinib and increase the risk of potentially life-threatening arrhythmias including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of aumolertinib states that concomitant use of moderate CYP3A4 inducers is not recommended.(1) The manufacturer of aumolertinib states that concurrent use of other drugs that are known to prolong the QTc interval should be avoided. If a suitable alternative is not available, consider increasing the frequency of ECG and electrolyte monitoring.(1) Consider obtaining serum calcium, magnesium, and potassium levels and correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If QTc prolongation occurs, follow recommended dose modifications: - Grade 2 (QTc interval >480 to 500 ms): Withhold aumolertinib for up to 2 weeks. If QTc interval has not recovered to <= 480 ms, permanently discontinue aumolertinib. If QTc interval recovers to <= 480 ms or within 30 ms of baseline, resume aumolertinib treatment at 110 mg. Monitor ECGs at least weekly for 2 weeks following return to <= 480 ms. Monitor and correct electrolytes and/or change concomitant medications. - Grade 3 (QTc interval > 500 ms or QTc interval increase of > 60 ms from baseline): Withhold aumolertinib for up to 2 weeks. If QTc interval has not recovered to <= 480 ms or within 30 ms of baseline, permanently discontinue aumolertinib. If QTc interval recovers to <= 480 ms and it is the first occurrence, resume treatment at 110 mg dose. If QTc interval recovers to <= 480 ms and it is the second occurrence or the first occurrence in patients with risk factors, resume treatment at 55 mg dose. Permanently discontinue aumolertinib if signs or symptoms recur at any time on the 55 mg dose. Monitor ECGs at least weekly for 2 weeks following return to <= 480 ms. Monitor and correct electrolytes and/or change concomitant medications. - QT interval prolongation associated with torsade de pointes, polymorphic ventricular tachycardia, or signs/symptoms of other serious arrhythmia: permanently discontinue aumolertinib.(1)

DISCUSSION: Aumolertinib is a CYP3A4 substrate.(1) The impact of moderate CYP3A4 inducers on the pharmacokinetics of aumolertinib has not been investigated in clinical studies. In a clinical study, aumolertinib area-under-curve (AUC) decreased by approximately 90% following concomitant use of rifampin (strong CYP3A4 inducer).(1) A concentration-QT analysis predicted a QTc interval prolongation at 110 mg aumolertinib of 9.06 ms (upper confidence interval = 11.01 ms) in 49 subjects.(1) In clinical studies (n=545), QT prolongation was reported in 51 patients (9.4%) treated with aumolertinib 110 mg. Seven patients (1.3%) had symptomatic events, including cardiac arrest, syncope, and ventricular arrhythmia. One patient with cardio-respiratory arrest and one patient with sudden cardiac death died. QTcF increase >60 ms occurred in 4.2% of patients, and increase in QTcF to >500 ms occurred in 0.9% of patients.(1) Moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, fexinidazole, pacritinib, and thioridazine.(3,4)

Moderate Cyp3a4 Inducers That Prolong Qt/Gepotidacin

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 that prolong QT may induce the metabolism of gepotidacin and result in additive effects on the QTc interval.(1,2)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers that prolong QT may result in decreased antimicrobial activity of gepotidacin and have additive effects on the QTc interval, which may result in potentially life-threatening arrhythmias including torsades de pointes.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of gepotidacin states that the concurrent use of QT prolonging agents in all patients should be avoided. If concurrent use cannot be avoided, obtain ECGs prior to initiating gepotidacin, during concomitant use, and as clinically indicated.(1) The manufacturer of gepotidacin recommends the following with moderate CYP3A4 inducers: Concomitant use of moderate CYP3A4 inducers in patients being treated for uncomplicated urogenital gonorrhea should be avoided.(1) For patients being treated for uncomplicated UTI, no dosage adjustment is needed when taken with moderate CYP3A4 inducers.(1) If concurrent therapy is warranted, correct any electrolyte abnormalities and instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Gepotidacin is primarily metabolized by CYP3A4.(1) Concomitant administration of efavirenz (moderate CYP3A4 inducer) and a single 1,500 mg dose of gepotidacin is predicted to decrease area-under-curve (AUC) and maximum concentration (Cmax) by 49% and 34%, respectively.(1) The effect of gepotidacin on the QTc interval was evaluated in a randomized, active (moxifloxacin 400 mg) and placebo-controlled, double-blind cross-over trial in healthy subjects who received single intravenous (IV) infusions of gepotidacin over 2 hours. A dose- and concentration-dependent QTc prolongation effect of gepotidacin was observed. The mean placebo-corrected change from baseline QTcF values around Tmax were 12 msec at 1,000 mg IV and 22 msec at 1,800 mg IV (not approved dosing regimens and route of administration). Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3) Moderate CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz, fexinidazole, pacritinib, and thioridazine.(3,4)

Moderate Cyp3a4 Inducers That Prolong Qt/Iv Lefamulin

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Lefamulin is a substrate of CYP3A4. Moderate inducers of CYP3A4 may induce the metabolism of lefamulin. Moderate CYP3A4 inducers that prolong the QTc interval may result in additive risk of QT prolongation.(1,2)

CLINICAL EFFECTS: The concurrent administration of a moderate CYP3A4 inducer that prolongs QT may result in decreased levels and effectiveness of lefamulin and cause additive effects on the QTc interval, which may result in life-threatening cardiac arrhythmias including torsades de pointes.(1,2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of lefamulin states that concurrent use with moderate CYP3A4 inducers should be avoided.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a study, concurrent administration of rifampin (strong inducer) with lefamulin injection decreased lefamulin area-under-the-curve (AUC) and maximum concentration (Cmax) by 28% and 8%.(1) Moderate inducers of CYP3A4 that prolong QT linked to this monograph include: fexinidazole and pacritinib.

Moderate Cyp3a4 Inducers/Abemaciclib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Abemaciclib is a substrate of CYP3A4. Moderate inducers of CYP3A4 may induce the metabolism of abemaciclib.(1)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of abemaciclib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of abemaciclib states to avoid concurrent administration with moderate CYP3A4 inducers and consider alternative agents.(1)

DISCUSSION: Abemaciclib is a substrate of CYP3A4.(1) Concurrent administration of rifampin (600 mg once daily, a strong CYP3A4 inducer) with a single 200 mg dose of abemaciclib decreased the relative potency adjusted unbound area-under-curve (AUC) of abemaciclib and its active metabolites (M2, M18, and M20) by 70% in healthy subjects.(1) Concurrent administration of efavirenz, bosentan, and modafinil (moderate CYP3A4 inducers) are predicted to decrease the relative potency adjusted unbound AUC of abemaciclib and its active metabolites (M2, M18, and M20) by 53%, 41%, and 29%, respectively.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, tipranavir/ritonavir and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Atogepant

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may increase the metabolism of atogepant by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of moderate CYP3A4 inducers with atogepant may result in decreased levels and clinical effectiveness of atogepant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of atogepant recommends that patients on concomitant moderate CYP3A4 inducers receive atogepant 60 mg once daily for prevention of episodic migraines and use of atogepant is not recommended for prevention of chronic migraines.(1) Patients receiving concurrent therapy with CYP3A4 inducers and atogepant should be observed for decreased clinical effectiveness.

DISCUSSION: In a study of healthy subjects, rifampin, a strong CYP3A4 inducer, decreased the area-under-curve (AUC) and maximum concentration (Cmax) of atogepant by 60% and 30%, respectively. Topiramate, a weak CYP3A4 inducer, decreased atogepant AUC and Cmax by 25% and 24%, respectively.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine and tovorafenib.(1,2)

Moderate Cyp3a4 Inducers/Brigatinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Brigatinib is a substrate of CYP3A4. Moderate inducers of CYP3A4 may induce the metabolism of brigatinib.(1)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of brigatinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of brigatinib states to avoid concurrent administration with moderate CYP3A4 inducers. If concurrent use cannot be avoided, increase the daily dose of brigatinib in 30 mg increments every 7 days, as tolerated, to a maximum of twice the brigatinib dose that was tolerated prior to initiation of the moderate CYP3A4 inducer. After discontinuation of a moderate CYP3A4 inducer, resume the brigatinib dose that was tolerated prior to initiation of the inducer.(1)

DISCUSSION: Brigatinib is a substrate of CYP3A4.(1) Concurrent administration of rifampin (600 mg daily, a strong CYP3A4 inducer) with a single 180 mg dose of brigatinib decreased the brigatinib maximum concentration (Cmax) by 60% and area-under-curve (AUC) by 80% compared to brigatinib alone. Moderate CYP3A4 inducers are expected to decrease the AUC of brigatinib by 50%.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat ethyl, thioridazine, tipranavir/ritonavir and tovorafenib.(2-3)

Moderate Cyp3a4 Inducers/Cabozantinib Lauryl Sulfate

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of cabozantinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of cabozantinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of moderate CYP3A4 inducers in patients receiving therapy with cabozantinib. Consider the use of alternative agents with less enzyme induction potential.(1) If concurrent use of a moderate CYP3A4 inducer cannot be avoided, increase the daily dose of cabozantinib CAPsules by 11.5 mg (from 34.5 mg to 46 mg daily, or from 23 mg to 34.5 mg daily, or from 11.5 mg to 23 mg daily) as tolerated. The daily dose of cabozantinib should not exceed 46 mg. If the CYP3A4 inducer is discontinued, reduce the dosage of cabozantinib to the dose used prior to initiation of the inducer 2 to 3 days after discontinuation of the moderate inducer.(1)

DISCUSSION: The impact of moderate CYP3A4 inducers on the pharmacokinetics of cabozantinib has not been investigated in clinical studies. In a study in healthy subjects, rifampin (strong CYP3A4 inducer, 600 mg daily for 31 days) decreased the AUC of a single dose of cabozantinib by 77%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Cabozantinib S-Malate Tablets

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of cabozantinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of cabozantinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of moderate CYP3A4 inducers in patients receiving therapy with cabozantinib. Consider the use of alternative agents with less enzyme induction potential.(1) If concurrent use of a moderate CYP3A4 inducer cannot be avoided, increase the daily dose of cabozantinib TABlets by 20 mg (e.g. from 60 mg to 80 mg daily) as tolerated. The daily dose should not exceed 80 mg. Resume the dose that was used prior to initiating the CYP3A4 inducer 2 to 3 days after discontinuation of the moderate inducer.(1)

DISCUSSION: The impact of moderate CYP3A4 inducers on the pharmacokinetics of cabozantinib has not been investigated in clinical studies. In a study in healthy subjects, rifampin (strong CYP3A4 inducer, 600 mg daily for 31 days) decreased the AUC of a single dose of cabozantinib by 77%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Camizestrant

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Agents that induce the CYP3A4 isoenzyme may induce the metabolism of camizestrant.(1)

CLINICAL EFFECTS: Concurrent use of moderate CYP3A4 inducers may decrease the levels and effectiveness of camizestrant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Dosage modifications for concomitant use of moderate CYP3A4 inducers differ depending on the CDK4/6 inhibitor used in combination with camizestrant.(1) Avoid the use of moderate CYP3A4 inducers for patients who are receiving camizestrant in combination with abemaciclib or palbociclib.(1) If concomitant use of a moderate CYP3A4 inducer cannot be avoided in patients who are receiving camizestrant in combination with abemaciclib or palbociclib, increase the camizestrant dosage from 75 mg once daily to 150 mg once daily. After the moderate CYP3A4 inducer has been discontinued for at least 14 days, resume the camizestrant dosage used prior to initiation of the moderate CYP3A4 inducer. For patients who are receiving camizestrant in combination with ribociclib concomitantly with a moderate CYP3A4 inducer, no camizestrant dosage modification is recommended.(1)

DISCUSSION: Camizestrant maximum concentration (Cmax) is predicted to decrease to 58%, and the area-under-curve (AUC) is predicted to decrease to 43% following concomitant administration of phenobarbital (moderate CYP3A4 inducer) 100 mg once daily for 17 days. Phenobarbital or efavirenz (moderate CYP3A4 inducer) are predicted to have minimal effects on camizestrant AUC and Cmax when camizestrant is given in combination with 400 mg or 600 mg ribociclib. Moderate inducers of CYP3A4 include: barbiturates, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, primidone, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Doravirine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate CYP3A4 inducers are expected to increase the metabolism of doravirine.(1-3)

CLINICAL EFFECTS: Concurrent or recent use of a moderate CYP3A4 inducer may result in decreased levels and effectiveness of doravirine.(1-3)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Recommendations for concurrent use of moderate CYP3A4 inducers with doravirine vary depending on the reference. The manufacturer of the fixed dose combination of doravirine-islatravir states concurrent use with moderate CYP3A4 inducers is not recommended.(3) The DHHS HIV guidelines state when coadministering doravirine with bosentan, dexamethasone, and eslicarbazepine (moderate CYP3A4 inducers): consider an alternative antiretroviral or alternative drug to the moderate CYP3A4 inducer. It would be prudent to consider alternative drugs to other moderate CYP3A4 inducers. If co-administration is necessary monitor virologic response.(4) The University of Liverpool HIV Drug Interactions Database states concurrent use with moderate CYP3A4 inducers should be avoided. If concurrent use cannot be avoided, dose adjustment of doravirine to 100 mg twice daily is recommended and should be maintained for at least 2 weeks following cessation of the moderate CYP3A4 inducer. If a patient is on eslicarbazepine, doravirine should not be coadministered.(5) The manufacturer of single ingredient doravirine and the fixed dose combination of doravirine-lamivudine-tenofovir does not have a recommendation for concurrent use with moderate CYP3A4 inducers.(1,3)

DISCUSSION: Doravirine is metabolized by CYP3A4. Moderate CYP3A4 inducers are expected to reduce doravirine levels, which may lead to loss of response.(1) In a study in 12 subjects, rifabutin (300 mg daily), a moderate CYP3A4 inducer, decreased the area-under-curve (AUC) and 24 hour concentration (C24) of a single dose of doravirine (100 mg) by 50% and 68%, respectively.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dexamethasone, dipyrone, elagolix, eslicarbazepine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat, thioridazine and tovorafenib.(3-4)

Moderate Cyp3a4 Inducers/Elbasvir-Grazoprevir

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Inducers of CYP3A4 may induce the metabolism of elbasvir and grazoprevir.(1,2)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of elbasvir and grazoprevir.(1,2)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Concurrent use of elbasvir-grazoprevir and a moderate CYP3A4 inducers is not recommended.(1,2) If concurrent use is required, monitor the patient for potential treatment failure and decreased elbasvir and grazoprevir levels.

DISCUSSION: In single dose studies, rifampin increased levels of both elbasvir and grazoprevir. In a study in 14 subjects, rifampin (600 mg single IV dose) increased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of a single dose of elbasvir (50 mg) by 41%, 22%, and 31%, respectively. In a study in 14 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of elbasvir (50 mg) by 29%, 17%, and 21%, respectively. In a study in 12 subjects, rifampin (600 mg single IV dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 10.94-fold, 10.21-fold, and 1.77-fold, respectively. In a study in 12 subjects, rifampin (600 mg single oral dose) increased the Cmax, AUC, and Cmin of a single dose of grazoprevir (200 mg) by 6.52-fold, 8.35-fold, and 1.61-fold, respectively.(1) However, multiple dose studies with rifampin showed decreased grazoprevir levels. In a study in 12 subjects, rifampin (600 mg orally) decreased the AUC and Cmin of grazoprevir (200 mg daily) by 7% and 90%, respectively. Cmax increased 16%.(1) In a study in 12 subjects, efavirenz (600 mg daily) decreased the Cmax, AUC, and Cmin of elbasvir (50 mg daily) by 45%, 34%, and 59%, respectively.(1) In a study in 12 subjects, efavirenz (600 mg daily) decreased the Cmax, AUC, and Cmin of grazoprevir (200 mg daily) by 87%, 82%, and 69%, respectively.(1) Moderate inducers of CYP3A4 include belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(1-4)

Moderate Cyp3a4 Inducers/Elinzanetant

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may induce the metabolism of elinzanetant by CYP3A4.(1,2)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may reduce the clinical effectiveness of elinzanetant.(1,2)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of elinzanetant states concurrent use with moderate CYP3A4 inducers should be avoided.(1) The Canadian manufacturer of elinzanetant states no dose adjustment is recommended for the concomitant use of elinzanetant with CYP3A4 and P-gp inducers.(2)

DISCUSSION: Elinzanetant maximum concentration (Cmax) reduced by 44% and area-under-curve (AUC) reduced by 64% following concomitant use with carbamazepine (moderate to strong CYP3A4 inducer) 600 mg administered twice daily.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(3,4)

Moderate Cyp3a4 Inducers/Erdafitinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Erdafitinib is a substrate of CYP2C9 and CYP3A4. Moderate inducers of CYP3A4 may induce the metabolism of erdafitinib.(1)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of erdafitinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of erdafitinib states that if a moderate CYP3A4 inducer must be co-administered, increase the erdafitinib dose to 9 mg daily. If a moderate CYP3A4 inducer is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity.(1)

DISCUSSION: Carbamazepine (a strong CYP3A4 inducer and weak CYP2C9 inducer) decreased the mean maximum concentration (Cmax) and area-under-curve (AUC) of erdafitinib by 78% and 45%, respectively.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2-3)

Moderate Cyp3a4 Inducers/Ibrutinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Agents that induce the CYP3A4 isoenzyme may induce the metabolism of ibrutinib.(1)

CLINICAL EFFECTS: Concurrent use of moderate CYP3A4 inducers may decrease the levels and effectiveness of ibrutinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of moderate CYP3A4 inducers in patients receiving therapy with ibrutinib.(1) Consider the use of alternative agents with less enzyme induction potential.(1)

DISCUSSION: The coadministration of rifampin decreased the maximum concentration (Cmax) and area-under-curve (AUC) of ibrutinib by more than 13-fold and 10-fold.(1) In a pharmacokinetic model, efavirenz (600 mg daily), a moderate CYP3A4 inducer, was predicted to decrease the Cmax and AUC of ibrutinib (560 mg) by 2.4-fold and 2.5-fold, respectively.(2) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(4)

Moderate Cyp3a4 Inducers/Lorlatinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 are expected to increase the metabolism of lorlatinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate inducers of CYP3A4 may result in decreased levels and effectiveness of lorlatinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concurrent administration of moderate inducers of CYP3A4 with lorlatinib.(1) If concurrent use of lorlatinib and moderate CYP3A4 inducers cannot be avoided, increase the dose of lorlatinib to 125 mg daily.(1)

DISCUSSION: Modafinil (a moderate CYP3A4 inducer) decreased the area-under-curve (AUC) and maximum concentration (Cmax) of a single 100 mg dose of lorlatinib by 23% and 22%, respectively.(1) Moderate inducers of CYP3A4 include belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, lesinurad, modafinil, nafcillin, pacritinib, pexidartinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(1)

Moderate Cyp3a4 Inducers/Mitapivat

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may increase the metabolism of mitapivat.(1)

CLINICAL EFFECTS: Concurrent use of a moderate CYP3A4 inducer may result in decreased levels and effectiveness of mitapivat.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Consider alternative therapies that are not moderate CYP3A4 inducers in patients who are on mitapivat. If concurrent use is necessary, monitor hemoglobin closely and titrate mitapivat dose, not to exceed a maximum dose of 100 mg twice daily.(1)

DISCUSSION: Mitapivat is a CYP3A4 substrate. In a pharmacokinetic study with 5 or 20 mg twice daily of mitapivat, efavirenz decreased area-under-curve (AUC) and concentration maximum (Cmax) by 60% and 30%, respectively. After mitapivat doses of 50 mg twice daily, efavirenz decreased AUC and Cmax by 55% and 24%, respectively.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, lesinurad, modafinil, nafcillin, pacritinib, pexidartinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Pirtobrutinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Pirtobrutinib is metabolized by CYP3A4. Moderate inducers of CYP3A4 may increase the metabolism of pirtobrutinib.(1)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of pirtobrutinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use of pirtobrutinib with moderate CYP3A4 inducers.(1) If concomitant use of moderate CYP3A4 inducers is unavoidable, and the current dose of pirtobrutinib is 200 mg daily, increase the dose to 300 mg daily. If the current pirtobrutinib dosage is 50 mg or 100 mg once daily, increase the dose by 50 mg.(1)

DISCUSSION: Efavirenz and bosentan (moderate CYP3A inducers) are predicted to decrease the area-under-curve (AUC) of pirtobrutinib by 49% and 27%, respectively.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, and thioridazine.(2,3)

Moderate Cyp3a4 Inducers/Pralsetinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of pralsetinib.(1)

CLINICAL EFFECTS: Concurrent use of a moderate CYP3A4 inducer may result in a loss of pralsetinib efficacy.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of pralsetinib with moderate CYP3A4 inducers.(1) If coadministration with a moderate CYP3A4 inducer cannot be avoided, increase the dose of pralsetinib on day 7 of coadministration with pralsetinib as follows: -If the current dose is 400 mg once daily, increase the dose to 600 mg daily. -If the current dose is 300 mg once daily, increase the dose to 500 mg daily. -If the current dose is 200 mg once daily, increase the dose to 300 mg daily. After discontinuation of a moderate CYP3A4 inducer for at least 14 days, resume the previous pralsetinib dose prior to initiating the moderate CYP3A4 inducer.(1) Monitor patients receiving concurrent therapy for reduced efficacy.

DISCUSSION: Coadministration of efavirenz 600 mg once daily is expected to decrease pralsetinib concentration maximum (Cmax) by 18% and area-under-curve (AUC) by 45%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2-3)

Moderate Cyp3a4 Inducers/Praziquantel

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of praziquantel.(1,2)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of praziquantel.(1,2)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of praziquantel recommends avoiding concomitant administration with moderate CYP3A4 inducers due to the risk of a clinically significant decrease in praziquantel plasma concentration which may lead to reduced therapeutic effect of praziquantel.(2) In patients receiving a clinically significant CYP3A4 inducer drug who need immediate treatment for schistosomiasis, alternative agents for schistosomiasis should be considered, where possible. If praziquantel treatment is necessary immediately, increase monitoring for reduced anthelmintic efficacy associated with praziquantel, when used in combination with a moderate CYP3A4 inducer.(2) In patients receiving a clinically significant CYP3A4 inducer drug whose treatment could be delayed, discontinue the CYP3A4 inducer drug at least 2 to 4 weeks before administration of praziquantel and, where possible, consider starting alternative medications that are not CYP3A4 inducers. The CYP3A4 inducer drug can be restarted 1 day after completion of praziquantel treatment, if needed.(2)

DISCUSSION: In a crossover study, 20 healthy subjects ingested a single 40 mg/kg oral dose of praziquantel following pre-treatment with oral efavirenz (400 mg daily for 13 days). Oral efavirenz reduced the mean praziquantel area-under-curve (AUC) by 77% and maximum concentration (Cmax) by 79%, when coadministered with praziquantel compared to praziquantel given alone.(2) Moderate CYP3A4 inducers include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(3-4)

Moderate Cyp3a4 Inducers/Ripretinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of ripretinib via this pathway.(1) Ripretinib and the active metabolite DP-5439 contribute to anticancer activity. CYP3A4 is the primary metabolism pathway for both ripretinib and the active metabolite DP-5439.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may alter the clinical effectiveness of ripretinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of ripretinib with moderate CYP3A4 inducers.(1-3) When possible, select alternative agents in place of the moderate CYP3A4 inducer. If the moderate CYP3A4 inducer cannot be avoided, increase the dose of ripretinib from 150 mg once daily to 150 mg twice daily during concurrent therapy. Monitor patients receiving concurrent therapy for reduced efficacy.(1-3) If the moderate CYP3A4 inducer is discontinued, reduce the dose of ripretinib back to 150 mg once daily 14 days after discontinuation of the moderate CYP3A4 inducer.(1-3) If a dose of ripretinib is missed (in patients taking twice daily dosing): -If less than 4 hours have passed since missed dose, patient should take the dose as soon as possible and then take the next dose at the regularly scheduled time. -If more than 4 hours have passed since missed dose, patient should skip the missed dose and then take the next dose at the regularly scheduled time.(1-3)

DISCUSSION: The primary metabolism pathway for ripretinib and DP-5439 is via CYP3A4.(1) In an interaction study of rifampin (a strong CYP3A inducer) and ripretinib, concurrent use decreased ripretinib concentration maximum (Cmax) by 18% and area-under-curve (AUC) by 61%, as well as decreased the active metabolite DP-5439 AUC by 57% and increased Cmax by 37%.(1) In a pharmacokinetic model of efavirenz (a moderate CYP3A inducer), concurrent use was predicted to decrease ripretinib Cmax by 24% and decrease AUC by 56%.(1) In the presence of a moderate CYP3A inducer, a doubled ripretinib dose (twice daily rather than once daily), is predicted to result in a 17% reduction in combined AUC of ripretinib and active metabolite DP-5439, compared to the usual recommended once daily dose with no inducer present.(2) In an interaction study of itraconazole (a strong CYP3A4 inhibitor) and ripretinib, concurrent use increased ripretinib Cmax by 36% and AUC by 99%. Concurrent use increased the AUC of DP-5439 by 99% with no change in Cmax.(1) Moderate CYP3A4 inducers linked to this monograph are: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(4,5)

Moderate Cyp3a4 Inducers/Sebetralstat

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may accelerate the metabolism of sebetralstat by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of sebetralstat and a moderate CYP3A4 inducer may result in decreased levels and effectiveness of sebetralstat.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of sebetralstat states that the concurrent use of moderate CYP3A4 inducers should be avoided.(1)

DISCUSSION: Sebetralstat maximum concentration (Cmax) decreased by 63% and area-under-curve (AUC) decreased by 79% following concomitant administration with efavirenz (a moderate CYP3A4 inducer) 600 mg once daily for 14 days. Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(2)

Moderate Cyp3a4 Inducers/Sunvozertinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may induce the metabolism of sunvozertinib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate CYP3A4 inducer may result in decreased levels and effectiveness of sunvozertinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of sunvozertinib states that concomitant use of moderate CYP3A4 inducers should be avoided.(1) If concurrent use cannot be avoided, increase sunvozertinib dose from 200 mg to 400 mg.(1) After stopping the CYP3A4 inducer, resume the prior sunvozertinib dose 7-14 days after stopping the CYP3A4 inducer.(1)

DISCUSSION: Sunvozertinib is primarily metabolized by CYP3A4.(1) Concomitant administration of sunvozertinib with a strong inducer (carbamazepine) resulted in a decrease in sunvozertinib area under the curve (AUC) and maximum concentration (Cmax) by 48% and 38%, respectively.(1) Sunvozertinib's AUC is predicted to decrease 44% with concurrent administration of efavirenz (600 mg daily; moderate CYP3A4 inducer).(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, rifabutin, repotrectinib, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2)

Moderate Cyp3a4 Inducers/Zanubrutinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Zanubrutinib is a substrate of CYP3A4. Moderate inducers of CYP3A4 may induce the metabolism of zanubrutinib.(1)

CLINICAL EFFECTS: The concurrent administration of moderate CYP3A4 inducers may result in decreased levels and effectiveness of zanubrutinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of zanubrutinib states that concurrent use with moderate CYP3A4 inducers should be avoided. If concurrent use cannot be avoided, increase zanubrutinib dosage to 320 mg twice daily.(1)

DISCUSSION: Co-administration of multiple doses of efavirenz, a moderate CYP3A4 inducer, is predicted to decrease zanubrutinib Cmax by 58% and AUC by 60%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, suzetrigine, telotristat ethyl, thioridazine, and tovorafenib.(2-3)

Myelosuppressives; Immunomodulators/Sodium Iodide I 131

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Sodium iodide I 131 can cause depression of the hematopoetic system. Myelosuppressives and immunomodulators also suppress the immune system.(1)

CLINICAL EFFECTS: Concurrent use of sodium iodide I 131 with agents that cause bone marrow depression, including myelosuppressives or immunomodulators, may result in an enhanced risk of hematologic disorders, including anemia, blood dyscrasias, bone marrow depression, leukopenia, and thrombocytopenia. Bone marrow depression may increase the risk of serious infections and bleeding.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of sodium iodide I 131 states that concurrent use with bone marrow depressants may enhance the depression of the hematopoetic system caused by large doses of sodium iodide I 131.(1) Sodium iodide I 131 causes a dose-dependent bone marrow suppression, including neutropenia or thrombocytopenia, in the 3 to 5 weeks following administration. Patients may be at increased risk of infections or bleeding during this time. Monitor complete blood counts within one month of therapy. If results indicate leukopenia or thrombocytopenia, dosimetry should be used to determine a safe sodium iodide I 131 activity.(1)

DISCUSSION: Hematologic disorders including death have been reported with sodium iodide I 131. The most common hematologic disorders reported include anemia, blood dyscrasias, bone marrow depression, leukopenia, and thrombocytopenia.(1)

Pacritinib/Duvelisib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Duvelisib is a substrate and moderate inhibitor of CYP3A4.(1) Pacritinib is a substrate and moderate inducer of CYP3A4.(2) Agents that induce the CYP3A4 isoenzyme may induce the metabolism of duvelisib.(1) Moderate CYP3A4 inhibitors may inhibit the CYP3A4 mediated metabolism of pacritinib.(2)

CLINICAL EFFECTS: Concurrent use of duvelisib and pacritinib may decrease the levels and effectiveness of duvelisib(1) while increasing levels and toxicity of pacritinib.(2) Elevated levels of pacritinib may result in QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(2) Other toxicities of pacritinib include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The concurrent use of duvelisib and pacritinib should be avoided.(1,2) The manufacturer recommendations for duvelisib are as follows: - If the moderate CYP3A4 inducer cannot be avoided, increase the dose of duvelisib on day 12 of concurrent therapy as follows: - If the initial dose of duvelisib is 25 mg twice daily, increase the duvelisib dose to 40 mg twice daily. - If the initial dose of duvelisib is 15 mg twice daily, increase the duvelisib dose to 25 mg twice daily. - Monitor patients receiving concurrent therapy for reduced efficacy.(1) - If the moderate CYP3A4 inducer is discontinued, reduce the dose of duvelisib back to the initial dose 14 days after discontinuation of the moderate CYP3A4 inducer.(1) The manufacturer recommendations for pacritinib are as follows: - If concurrent use cannot be avoided, monitor patients for increased adverse reactions from pacritinib and consider pacritinib dose modifications based on safety.(2) - If coadministration is unavoidable, monitor for prolongation of the QTc interval.(1,2) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. - If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(2)

DISCUSSION: In an interaction study, etravirine (a moderate CYP3A inducer) 200 mg twice daily decreased the maximum concentration (Cmax) and area-under-curve (AUC) of single dose duvelisib 25 mg by 16% and 35%, respectively.(1) Clarithromycin (500 mg twice daily for 5 days, a strong CYP3A4 inhibitor) increased Cmax and AUC of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(2) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(2) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(2)

Pacritinib/Lenacapavir

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Lenacapavir is a substrate and moderate inhibitor of CYP3A4.(1) Pacritinib is a substrate and moderate inducer of CYP3A4.(2) Agents that induce the CYP3A4 isoenzyme may induce the metabolism of lenacapavir.(1) Moderate CYP3A4 inhibitors may inhibit the CYP3A4 mediated metabolism of pacritinib.(2)

CLINICAL EFFECTS: Concurrent use of lenacapavir and pacritinib may decrease the levels and effectiveness of lenacapavir(1) while increasing levels and toxicity of pacritinib.(2) Elevated levels of pacritinib may result in QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(2) Other toxicities of pacritinib include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The concurrent use of lenacapavir and pacritinib should be avoided.(1,2) If concurrent use cannot be avoided, monitor patients for increased adverse reactions from pacritinib and consider pacritinib dose modifications based on safety.(2) If coadministration is unavoidable, monitor for prolongation of the QTc interval.(1,2) When concurrent therapy is warranted: consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(2)

DISCUSSION: In a study, efavirenz 600 mg once daily (inducer of CYP3A4 [moderate]) decreased the maximum concentration (Cmax) and area-under-curve (AUC) of lenacapavir by 36% and 56%, respectively.(1) Clarithromycin (500 mg twice daily for 5 days, a strong CYP3A4 inhibitor) increased Cmax and AUC of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(2) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(2) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(2)

Pacritinib/Moderate Cyp3a4 Inhibitors That Prolong Qt

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate inhibitors of CYP3A4 that prolong the QTc interval may inhibit the metabolism of pacritinib and result in additive risk of QT prolongation.(1)

CLINICAL EFFECTS: Concurrent use of moderate CYP3A4 inhibitors that prolong QT may increase the levels and effects of pacritinib, including additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(1) Other toxicities include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of pacritinib states concurrent use with agents known to prolong the QT interval should be avoided. Avoid the use of pacritinib in patients with a baseline QTc > 480 msec. Correct hypokalemia prior to initiation and during therapy with pacritinib.(1) The manufacturer of pacritinib recommends monitoring patients concomitantly receiving moderate CYP3A4 inhibitors (e.g., fluconazole) for increased adverse reactions and considering pacritinib dose modifications based on safety.(1) When concurrent therapy is warranted monitor for prolongation of the QTc interval.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(1)

DISCUSSION: Fluconazole (200 mg once daily for 7 days, a moderate CYP3A4 inhibitor) increased maximum concentration (Cmax) and area-under-curve (AUC) of pacritinib (200 mg twice daily at steady state) by 41% and 45%, respectively.(1) Concomitant use of pacritinib with doses of fluconazole greater than 200 mg once daily have not been studied.(1) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(5) Moderate inhibitors of CYP3A4 that prolong QT include: clofazimine.(3,4)

Pacritinib/Oral Lefamulin

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Lefamulin and pacritinib are both metabolized by CYP3A4. Pacritinib is a moderate CYP3A4 inducer while oral lefamulin is a moderate CYP3A4 inhibitor.(1-2)

CLINICAL EFFECTS: The net effect of coadministration of lefamulin and pacritinib on CYP3A4 enzyme activity is unknown. Concurrent or recent use of pacritinib may either decrease the clinical effectiveness of lefamulin(1) or increase the levels and toxicities of pacritinib.(1,2) Concurrent use may result in additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(1,2) Other toxicities of pacritinib include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: There are no recommendations for concurrent use of lefamulin with pacritinib. Concurrent use of lefamulin with pacritinib should be avoided.(1) If concurrent use cannot be avoided, monitor patients for increased adverse reactions from pacritinib and consider pacritinib dose modifications based on safety.(2) If coadministration is unavoidable, monitor for prolongation of the QTc interval.(1,2) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(2)

DISCUSSION: In a study, concurrent administration of rifampin (a strong CYP3A4 inducer) with oral lefamulin (tablets) decreased lefamulin area-under-curve (AUC) and maximum concentration (Cmax) by 72% and 57%.(1) In a study, oral lefamulin tablets administered concomitantly with and at 2 or 4 hours before oral midazolam (a CYP3A4 substrate) increased the AUC and Cmax of midazolam by 200% and 100%, respectively. No clinically significant effect on midazolam pharmacokinetics was observed when co-administered with lefamulin injection.(1) Clarithromycin (500 mg twice daily for 5 days) increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of pacritinib (400 mg) by 30% and 80%, respectively.(2) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(2) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(2)

Pacritinib/Qt Prolonging Agents

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Pacritinib has been observed to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of pacritinib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of pacritinib states concurrent use with agents known to prolong the QT interval should be avoided. Avoid the use of pacritinib in patients with a baseline QTc > 480 msec. Correct hypokalemia prior to initiation and during therapy with pacritinib.(1) If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a 24 week clinical study, patients treatment with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3)

Pacritinib/Voxelotor

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Voxelotor and pacritinib are both metabolized by CYP3A4. Voxelotor is a moderate inhibitor of CYP3A4 while pacritinib is a moderate CYP3A4 inducer.(1-2)

CLINICAL EFFECTS: Concurrent use of voxelotor and pacritinib may decrease the levels and effectiveness of voxelotor(2) while increasing levels and toxicity of pacritinib.(1) Elevated levels of pacritinib may result in QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(1) Other toxicities of pacritinib include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The effect of the two-way inhibition and induction of pacritinib and voxelotor metabolism is unknown. The optimal doses of pacritinib and voxelotor when used concurrently have not been determined. Concurrent use should be avoided. Dose modifications mentioned below are informational only. The manufacturer of pacritinib recommends monitoring patients concomitantly receiving moderate CYP3A4 inhibitors for increased adverse reactions and considering pacritinib dose modifications based on safety.(1) When concurrent therapy is warranted monitor for prolongation of the QTc interval.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(1) The manufacturer of voxelotor states that concurrent use with strong or moderate CYP3A4 inducers should be avoided. If concomitant use is unavoidable, increase the dose of voxelotor as follows: -Patients 12 years and older on concurrent strong CYP3A4 inducers: increase voxelotor dose to 2,500 mg daily. -Patients 12 years and older on concurrent moderate CYP3A4 inducers: increase voxelotor dose to 2,000 mg daily. -Patients 4 years to less than 12 years on concurrent strong or moderate CYP3A4 inducers: refer to prescribing information for recommended weight-based dosage adjustments.(2)

DISCUSSION: Fluconazole (200 mg once daily for 7 days, a moderate CYP3A4 inhibitor) increased maximum concentration (Cmax) and area-under-curve (AUC) of pacritinib (200 mg twice daily at steady state) by 41% and 45%, respectively.(1) Concomitant use of pacritinib with doses of fluconazole greater than 200 mg once daily have not been studied.(1) Clarithromycin (500 mg twice daily for 5 days, a strong CYP3A4 inhibitor) increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of pacritinib (400 mg) by 80% and 30%, respectively.(1) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Co-administration of efavirenz, a moderate CYP3A4 inducer, is predicted to decrease the AUC of voxelotor by 24%.(2)

Select Cyp2c19 Or Cyp3a4 Inducer/Esomeprazole; Omeprazole

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Proton pump inhibitors are primarily metabolized by CYP2C19, while CYP3A4 also plays a role in metabolism.(1,2) Enzalutamide, rifampin, and St. John's wort are moderate inducers of CYP2C19 and strong inducers of CYP3A4.(3,4) Apalutamide is a strong inducer of CYP2C19 and CYP3A4.(5) Efavirenz and pacritinib are moderate inducers of CYP2C19 and CYP3A4.(3,6) Sparsentan is a moderate inducer of CYP2C19.(8) Fexinidazole is a moderate inducer of CYP3A4.(3)

CLINICAL EFFECTS: Concurrent use of agents which induce both CYP2C19 and CYP3A4 decrease systemic exposure and may result in decreased effectiveness of proton pump inhibitors.(1-7)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concurrent use of esomeprazole or omeprazole with CYP2C19 or CYP3A4 inducers.(1,2) Monitor patients receiving concurrent therapy for reduced proton pump inhibitor (PPI) effectiveness. Although specific dosing recommendations are not available, a higher dose of the proton pump inhibitor may be considered to maintain PPI efficacy.

DISCUSSION: In an interaction study, subjects with prostate cancer received omeprazole before and after enzalutamide 160 mg daily for at least 55 days. Enzalutamide decreased omeprazole area-under-curve (AUC) by 70.5%.(3,4) In an interaction study, rifampin 600 mg daily for 7 days decreased omeprazole AUC by 89.5%.(3,7) In an interaction study, pacritinib 200 mg twice daily at steady state decreased the Cmax and AUC of a single dose of omeprazole (20 mg) by 27% and 51%, respectively.(6) Concomitant use with sparsentan (moderate CYP2C19 inducer) decreased the exposure of omeprazole Cmax by 49% and AUC by 60%.(8) In an interaction study, St. John's wort decreased the maximum concentration (Cmax) and AUC of omeprazole by 37.5% and 49.6%, respectively. The Cmax and AUC of omeprazole sulfone (via CYP2C19) increased by 160.3% and 136.6%, respectively. The Cmax and AUC of 5-hydroxyomeprazole (via CYP3A4) increased by 38.1% and 37.2%, respectively.(9,10)

Selected Inhibitors Of Bcrp/Cladribine Oral

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Inhibitors of BCRP may increase the absorption of cladribine.(1-2)

CLINICAL EFFECTS: The concurrent administration of cladribine with an inhibitor of BCRP may result in elevated levels of cladribine and signs of toxicity.(1-2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of cladribine states concurrent use of BCRP inhibitors should be avoided during the 4- to 5-day cladribine treatment.(1-2) Selection of an alternative concurrent medication with no or minimal transporter inhibiting proprieties should be considered. If this is not possible, dose reduction to the minimum mandatory dose of the BCRP inhibitor, separation in timing of administration, and careful patient monitoring is recommended.(1-2) Monitor for signs of hematologic toxicity. Lymphocyte counts should be monitored.

DISCUSSION: Cladribine is a substrate of BCRP. Inhibitors of this transporter are expected to increase cladribine levels.(1-2) BCRP inhibitors linked to this monograph include: capmatinib, clopidogrel, curcumin, danicopan, darolutamide, dasabuvir, eltrombopag, enasidenib, ensitrelvir, febuxostat, fostamatinib, fostemsavir, glecaprevir/pibrentasvir, grazoprevir, lazertinib, oteseconazole, pacritinib, paritaprevir, regorafenib, resmetirom, ritonavir, rolapitant, roxadustat, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tafamidis, ticagrelor, tolvaptan, turmeric, vadadustat, and zongertinib.(1-4)

Selected Moderate And Weak Cyp1a2 Inhibitors/Tizanidine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Moderate and weak CYP1A2 inhibitors may inhibit the metabolism of tizanidine by CYP1A2.(1)

CLINICAL EFFECTS: Concurrent use of moderate and weak CYP1A2 inhibitors may result in elevated levels of and effects from tizanidine, including hypotension, bradycardia, drowsiness, sedation, and decreased psychomotor function.

PREDISPOSING FACTORS: The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(2)

PATIENT MANAGEMENT: The US manufacturer of tizanidine states that concurrent use of tizanidine with inhibitors of CYP1A2 should be avoided.(3) If adverse reactions such as hypotension, bradycardia or excessive drowsiness occur, reduce tizanidine dosage or discontinue tizanidine therapy.(3)

DISCUSSION: In a study, cannabidiol 750 mg twice daily (a weak CYP1A2 inhibitor) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a 200 mg single dose of caffeine (a sensitive CYP1A2 substrate) by 15% and 95%, respectively.(1) In a study in 10 healthy subjects, concurrent fluvoxamine, a strong inhibitor of CYP1A2, increased tizanidine Cmax, AUC, and half-life (T1/2) by 12-fold, 33-fold, and 3-fold, respectively. Significant decreases in blood pressure and increases in drowsiness and psychomotor impairment occurred.(3) In a study in 10 healthy subjects, concurrent ciprofloxacin, a strong inhibitor of CYP1A2, increased tizanidine Cmax and AUC by 7-fold and 10-fold, respectively. Significant decreases in blood pressure and increases in drowsiness and psychomotor impairment occurred.(3) Moderate CYP1A2 inhibitors linked to this monograph include: centanafadine, dipyrone, fexinidazole, genistein, methoxsalen, phenylpropanolamine, pipemidic acid, propranolol, rucaparib, and troleandomycin. Weak CYP1A2 inhibitors linked to this monograph include: allopurinol, artemisinin, belumosudil, caffeine, cannabidiol, curcumin, dan-shen, disulfiram, Echinacea, ginseng, parsley, piperine, ribociclib, simeprevir, thiabendazole, and triclabendazole.(4)

Selected Qt Prolonging Agents/Ziprasidone

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Ziprasidone has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of ziprasidone with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(1,3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3)

PATIENT MANAGEMENT: The manufacturer of ziprasidone states under contraindications that ziprasidone should not be used with other drugs that prolong the QT interval such as dofetilide, sotalol, quinidine, other Class Ia and III anti-arrhythmics, mesoridazine, thioridazine, chlorpromazine, droperidol, pimozide, sparfloxacin, gatifloxacin, moxifloxacin, halofantrine, mefloquine, pentamidine, arsenic trioxide, levomethadyl acetate, dolasetron mesylate, probucol or tacrolimus.(1) It would be prudent to avoid the use of ziprasidone with medicines suspected of prolonging the QT interval. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(2)

Strong & Moderate Cyp3a4 Inducers/Guanfacine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Strong or moderate inducers of CYP3A4 may induce the metabolism of guanfacine.(1)

CLINICAL EFFECTS: The concurrent administration of a strong or moderate CYP3A4 inducer may result in decreased levels and effectiveness of guanfacine.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Patients maintained on guanfacine may need dosage adjustments if strong or moderate inducers of CYP3A4 are initiated or discontinued. The manufacturer of extended-release guanfacine recommends a starting dose of extended-release guanfacine initiated at up to double the recommended level of the weight based dosing in patients receiving strong or moderate inducers of CYP3A4. If a patient has been maintained on extended-release guanfacine and is started on a strong or moderate CYP3A4 inducer, the dose of extended-release guanfacine should be increased up to double the recommended weight based dose over 1 to 2 weeks. If a patient has been maintained on extended-release guanfacine and a strong or moderate CYP3A4 inducer, and the strong or moderate CYP3A4 inducer is discontinued, the dose of extended-release guanfacine may need to be decreased to the recommended weight based dose over 1 to 2 weeks. Extended-release guanfacine target dose range for attention deficit hyperactivity disorder is 0.05-0.12 mg/kg/day. Doses above 4 mg/day have not been evaluated in children ages 6-12 years and doses above 7 mg/day have not been evaluated in adolescents ages 13-17 years.(1)

DISCUSSION: Rifampin (dosage not stated), a strong inducer of CYP3A4, decreased the maximum concentration (Cmax) and area-under-curve (AUC) of guanfacine (dosage not stated) by approximately 50%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifabutin, rifampin, rifapentine, and St. John's wort.(1-3) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat, thioridazine, and tovorafenib.(1-3)

Strong & Moderate Cyp3a4 Inducers/Olaparib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Agents that induce the CYP3A4 isoenzyme may induce the metabolism of olaparib.(1)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers may decrease the levels and effectiveness of olaparib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid the concurrent use of strong or moderate CYP3A4 inducers in patients receiving therapy with olaparib.(1) Consider the use of alternatives with little to no induction potential.

DISCUSSION: In a drug interaction trial, olaparib area-under-curve (AUC) and maximum concentration (Cmax) decreased 87% and 71% respectively when olaparib was administered with rifampin. Based upon simulated models, a moderate CYP3A4 inducer is predicted to decrease olaparib AUC by 50-60% and Cmax by 20-30%.(1-3) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort. Moderate inducers of CYP3A4 include: bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(4-5)

Strong And Mod Cyp3a4 Inducers That Prolong Qt/Entrectinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Entrectinib is a substrate of CYP3A4. Strong and moderate inducers of CYP3A4 that prolong QT may induce the metabolism of entrectinib and result in additive risk of QT prolongation.(1,2)

CLINICAL EFFECTS: The concurrent administration of a strong or moderate CYP3A4 inducer that prolongs QT may result in decreased levels and effectiveness of entrectinib and may cause additive effects on the QTc interval, which may result in life-threatening cardiac arrhythmias including torsades de points.(1,2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of entrectinib states that concurrent use with strong or moderate CYP3A4 inducers should be avoided.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Concomitant administration of rifampin (strong CYP3A4 inducer) with a single 600 mg entrectinib dose decreased entrectinib maximum concentration (Cmax) and area-under-the-curve (AUC) by 56% and 77%.(1) Coadministration with a moderate CYP3A4 inducer is predicted to decrease entrectinib's AUC and Cmax by 56% and 43%.(1) Strong and moderate inducers of CYP3A4 that prolong QT include: efavirenz, encorafenib, fexinidazole, ivosidenib, pacritinib, and thioridazine.(3,4)

Strong And Moderate Cyp3a4 Inducers/Cariprazine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Cariprazine and its major active metabolite DDCAR are metabolized by CYP3A4. Strong and moderate inducers of CYP3A4 may accelerate the metabolism of cariprazine.(1-4)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 may result in decreased levels and effectiveness of cariprazine.(1-4)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of cariprazine does not recommend concurrent use of strong CYP3A4 inducers.(1) The Australian, Canadian, and UK manufacturers of cariprazine state that concurrent use of strong and moderate CYP3A4 inducers is contraindicated.(2-4)

DISCUSSION: Cariprazine and its active metabolites are primarily metabolized by CYP3A4. Coadministration with CYP3A4 inducers has not been studied and the net effect is unclear. Due to the long half life of the active metabolites, it takes several weeks for cariprazine to reach steady state after dosage changes.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(5-6) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(5-6)

Strong And Moderate Cyp3a4 Inducers/Pretomanid

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may induce the metabolism of pretomanid by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong and moderate CYP3A4 inducers and pretomanid may result in decreased levels and clinical effectiveness of pretomanid.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of pretomanid recommends avoiding concurrent use with strong or moderate CYP3A4 inducers during pretomanid therapy.(1) Patients receiving concurrent therapy with strong and moderate CYP3A4 inducers and pretomanid should be observed for decreased levels and clinical effectiveness.

DISCUSSION: In a clinical study, concurrent use of pretomanid 200 mg with efavirenz 600 mg for 7 days resulted in decreased mean area-under-curve (AUC) by 35% and maximum concentration (Cmax) by 28%.(1) In a clinical study, concurrent use of pretomanid 200 mg with rifampin 600 mg for 7 days resulted in decreased mean AUC by 66% and Cmax by 53%.(1) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, etravirine, fexinidazole, fosphenytoin, ivosidenib, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, rifampin, rifapentine, St. John's wort, sotorasib, telotristat, thioridazine, and tovorafenib.(1,2)

Strong And Moderate Cyp3a4 Inducers/Velpatasvir

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Strong or moderate CYP3A4 inducers may induce the metabolism of velpatasvir via CYP3A4.(1,2)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers may result in decreased levels and effectiveness of velpatasvir.(1,2)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The concurrent use of velpatasvir with strong or moderate CYP3A4 inducers is not recommended.(1,2)

DISCUSSION: In an interaction study, efavirenz 600 mg daily (in combination with emtricitabine-tenofovir DF) decreased velpatasvir concentration maximum (Cmax) and area-under-curve (AUC) by 47% and 53%, respectively.(1) In an interaction study, rifampin 600 mg daily decreased velpatasvir Cmax and AUC by 71% and 82%, respectively.(1) Strong and moderate CYP3A4 inducers include: belzutifan, bosentan, cenobamate, dabrafenib, elagolix, enzalutamide, fexinidazole, ivosidenib, lesinurad, lumacaftor, mavacamten, methimazole, mitapivat, mitotane, modafinil, nafcillin, pacritinib, pexidartinib, sotorasib, telotristat, thioridazine, and tovorafenib.(3)

Strong Or Moderate Cyp3a4 Inducer And Substrates/Avacopan

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Avacopan is moderate inhibitor and substrate of CYP3A4. Strong or moderate inducers of CYP3A4 may induce the metabolism of avacopan.(1) Avacopan may inhibit the metabolism of CYP3A4 substrates.(1)

CLINICAL EFFECTS: The concurrent administration of strong or moderate CYP3A4 inducers may result in decreased levels and effectiveness of avacopan.(1) Concurrent administration of avacopan with CYP3A4 substrates may result in increased levels and side effects of the CYP3A4 substrate.(1) If the patient is on fexinidazole, concurrent administration of avacopan with fexinidazole may result in decreased levels of fexinidazole's active metabolite, resulting in decreased efficacy.(2)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of avacopan states that concurrent use with strong or moderate CYP3A4 inducers should be avoided.(1) Consider dose reduction of CYP3A4 substrates when coadministering avacopan with CYP3A4 substrates. Consult the concomitant CYP3A4 substrate product information when considering administration with avacopan.(1) The manufacturer of fexinidazole states that concurrent use with moderate CYP3A4 inhibitors should be avoided.(2)

DISCUSSION: Co-administration of rifampin 600 mg once daily for 11 days, a strong CYP3A4 inducer, decreased the avacopan maximum concentration (Cmax) by 79% and area-under-curve (AUC) by 93%.(1) In a study, avacopan 60 mg twice daily with food was administered for 7 days with simvastatin. Since it takes 13 weeks to reach steady state, this high dose of avacopan was used to achieve systemic levels similar to those achieved at steady state with a dose of 30 mg twice daily with food. Avacopan increased the AUC and Cmax of simvastatin by 3.53-fold and 3.20-fold, respectively.(1) Moderate inducers and substrates of CYP3A4 include: bosentan, encorafenib, fexinidazole, ivosidenib, mavacamten, pacritinib, pexidartinib, and repotrectinib.(3-4)

Strong Or Moderate Cyp3a4 Inducers/Ganaxolone

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Ganaxolone is a substrate of CYP3A4. Strong or moderate inducers of CYP3A4 may induce the metabolism of ganaxolone.(1)

CLINICAL EFFECTS: The concurrent administration of strong or moderate CYP3A4 inducers may result in decreased levels and effectiveness of ganaxolone.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of ganaxolone states that concurrent use with strong or moderate CYP3A4 inducers should be avoided. If concurrent use is unavoidable, consider increasing the dose of ganaxolone. Do not exceed the recommended maximum daily dose.(1) In patients who are stable on ganaxolone and are initiated on anticonvulsants that are CYP3A4 inducers, consider increasing the dose of ganaxolone. Do not exceed the recommended maximum daily dose.(1)

DISCUSSION: Co-administration of rifampin, a strong CYP3A4 inducer, decreased the ganaxolone concentration maximum (Cmax) by 57% and area-under-curve (AUC) by 68%.(1) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort. Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2-3)

Strong Or Moderate Cyp3a4 Inducers/Simeprevir

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Strong or moderate inducers of CYP3A4 may induce the metabolism of simeprevir.(1)

CLINICAL EFFECTS: Concurrent or recent use of strong or moderate CYP3A4 inducers may lower simeprevir minimum concentrations (Cmin) leading to a loss of virologic response to simeprevir.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of simeprevir states that concurrent administration of strong or moderate inducers of CYP3A4 is not recommended due risk for simeprevir treatment failure.(1)

DISCUSSION: In a study in 18 subjects, rifampin (600 mg daily for 7 days) decreased the area-under-curve (AUC) and Cmin of simeprevir (200 mg daily for 7 days) by 48% and 92%, respectively. The simeprevir maximum concentration (Cmax) increased 1.31-fold.(1) Strong and moderate inducers of CYP3A4 linked to this monograph include apalutamide, barbiturates, belzutifan, bosentan, carbamazepine, cenobamate, dabrafenib, dexamethasone, elagolix, encorafenib, enzalutamide, fosphenytoin, ivosidenib, fexinidazole, lesinurad, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, oxcarbazepine, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifampin, rifabutin, rifapentine, St. John's wort, sotorasib, telotristat, and tovorafenib.(1-3)

Moderate Interaction: Assess the risk to the patient and take action as needed.

Moderate And Weak Cyp3a4 Inducers That Prolong Qt/Tacrolimus

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate or weak CYP3A4 inducers may accelerate the metabolism of tacrolimus.(1) In addition, concurrent use of tacrolimus and other agents that prolong the QT interval may result in additive or synergistic effects on the QTc interval.(1)

CLINICAL EFFECTS: Concurrent use of a moderate or weak CYP3A4 inducer may result in decreased levels and effectiveness of tacrolimus.(1) In addition, concurrent administration of QT prolonging agents and tacrolimus may result in additive prolongation of the QTc interval and life-threatening cardiac arrhythmias, including torsades de pointes.

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of tacrolimus recommends monitoring tacrolimus whole blood trough concentrations and adjusting tacrolimus dose if needed. Monitor clinical response closely.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: A 13-year-old cystic fibrosis patient with a history of liver transplant on stable doses of tacrolimus underwent 2 separate courses of nafcillin therapy (a moderate CYP3A4 inducer). During the 1st course of nafcillin, his tacrolimus levels started to fall 3 days after starting nafcillin, became undetectable at day 8, and recovered to therapeutic levels without a change in tacrolimus dose 5 days after discontinuation of nafcillin. During the 2nd course of nafcillin, tacrolimus level became undetectable 4 days after starting nafcillin and recovered 3 days after stopping nafcillin.(3) Tacrolimus has been associated with QT prolongation.(1) In a kidney transplant population, 98 patients received immunosuppressive management with tacrolimus, cyclosporine, everolimus, or azathioprine. All patients post-transplant had significantly prolonged QTc interval compared to pre-transplant in all groups.(4) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(5) Moderate inducers of CYP3A4 that prolong QT include: efavirenz, fexinidazole, pacritinib, and thioridazine.(6,7) Weak inducers of CYP3A4 that prolong QT include: aumolertinib, pitolisant and vemurafenib.(6,7)

Moderate Cyp3a4 Inducers/Aficamten

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Aficamten is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of aficamten.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may decrease the levels and effectiveness of aficamten and increase the risk of developing heart failure due to systolic dysfunction.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: In patients who are on stable concurrent therapy with aficamten and a moderate to strong CYP3A4 inducer, reduce the dose of aficamten when discontinuing the inducer as follows: -If the current dose is 20 mg daily, reduce to 10 mg daily. -If the current dose is 15 mg daily, reduce to 5 mg daily. -If the current dose is 10 mg daily, reduce to 5 mg daily. -If the current dose is 5 mg daily, maintain 5 mg daily. Assess LVEF 2 to 8 weeks after discontinuation of such inducers and adjust the dose of aficamten accordingly.(1)

DISCUSSION: In a study, carbamazepine (moderate to strong CYP3A4 inducer, weak CYP2C9 inducer) decreased aficamten's area-under-curve (AUC) 51%.(1) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Crinecerfont

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of crinecerfont.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may reduce the clinical effectiveness of crinecerfont.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of crinecerfont states that concurrent use of moderate CYP3A4 inducers requires a dose adjustment of crinecerfont. Increase the evening dose of crinecerfont by 2-fold. Do not increase the morning dose. In adults, increase the dosage of crinecerfont to 100 mg in the morning and 200 mg in the evening. In pediatric patients 4 years and older weighing: - 10 kg to <20 kg: increase the crinecerfont dosage to 25 mg in the morning and 50 mg in the evening, - 20 kg to <55 kg: increase the crinecerfont dosage to 50 mg in the morning and 100 mg in the evening, - >=55 kg: increase the crinecerfont dosage to 100 mg in the morning and 200 mg in the evening.(1)

DISCUSSION: In a study, concomitant use of rifampin (strong CYP3A4 inducer) decreased crinecerfont maximum concentration (Cmax) by 23% and area-under-curve (AUC) by 62%.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Daclatasvir

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of daclatasvir.(1)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 without a dosage adjustment of daclatasvir is expected to reduce levels and effectiveness of daclatasvir.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The dose of daclatasvir should be increased to 90 mg once daily in patients receiving moderate inducers of CYP3A4.(1)

DISCUSSION: Efavirenz (600 mg daily) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of daclatasvir by 17%, 32%, and 59%, respectively.(1) Moderate inducers of CYP3A4 include belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(1-3)

Moderate Cyp3a4 Inducers/Daraxonrasib (>= 400 Mg)

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Daraxonrasib is a CYP3A4 substrate. Moderate CYP3A4 inducers may induce the metabolism of daraxonrasib.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may decrease the levels and effectiveness of daraxonrasib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of daraxonrasib states that concomitant use of moderate CYP3A4 inducers requires a dose increase of daraxonrasib to 400 mg once daily.(1)

DISCUSSION: In a clinical study, daraxonrasib area-under-curve (AUC) is predicted to decrease by 50-84% with concomitant use of efavirenz 600 mg once daily and modafinil 400 mg once daily (moderate CYP3A4 inducers).(1) Moderate CYP3A4 inducers linked to this monograph include: asunaprevir, belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lopinavir, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, telotristat, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Larotrectinib

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may increase the metabolism of larotrectinib.(1)

CLINICAL EFFECTS: Concurrent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of larotrectinib.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of larotrectinib states that the concurrent use of moderate CYP3A4 inducers requires a dose modification. Double the dose of larotrectinib when coadministered with moderate CYP3A4 inducers. After the moderate CYP3A4 inducer has been discontinued for 3 to 5 elimination half-lives, resume the larotrectinib dose at the dose taken prior to initiating the CYP3A4 inducer.(1)

DISCUSSION: In a study, efavirenz (a moderate CYP3A4 inducer) was predicted to decrease area-under-curve (AUC) and maximum concentration (Cmax) by 72% and 60%, respectively, compared to larotrectinib administered alone.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(3-4)

Moderate Cyp3a4 Inducers/Paltusotine

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may induce the metabolism of paltusotine.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may alter the clinical effectiveness of paltusotine.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Patients taking moderate CYP3A4 inducers may require an increased dosage of paltusotine.(1) The manufacturer of paltusotine states do not exceed two-fold the paltusotine dosage prior to concomitant use or 120 mg daily, whichever is less.(1) Monitor patients receiving concurrent therapy for reduced efficacy.

DISCUSSION: Paltusotine is metabolized by CYP3A4.(1) Moderate CYP3A4 inducers such as efavirenz are predicted to decrease concentration maximum (Cmax) and area-under-curve (AUC) of paltusotine approximately 5% and 30%, respectively.(1) In an interaction study, paltusotine concentration maximum (Cmax) and area-under-curve (AUC) decreased by 44% and 70%, respectively, following concomitant administration of carbamazepine (strong CYP3A inducer).(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Rolapitant

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Rolapitant is metabolized primarily by CYP3A4. Moderate inducers of CYP3A4 may increase the metabolism and clearance of rolapitant via CYP3A4.(1)

CLINICAL EFFECTS: Concurrent use with moderate inducers of CYP3A4 may result in significantly decreased levels and effectiveness of rolapitant.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The UK manufacturer of rolapitant states that rolapitant is not recommended in patients already taking moderate CYP3A4 inducers.(1) If concomitant use is warranted, monitor the patient for decreased antiemetic efficacy. When possible and clinically appropriate, consider use of an alternative antiemetic or alternatives to the moderate CYP3A4 inducer.

DISCUSSION: The effect of moderate CYP3A4 inducers on rolapitant has not been studied. The UK manufacturer of rolapitant does not recommend the concurrent use of rolapitant with moderate CYP3A4 inducers. Rifampin (600 mg daily for 14 days), a strong CYP3A4 inducer, decreased the Cmax and AUC of a single dose of rolapitant (180 mg on Day 7) by 30% and 85%, respectively. The half-life of rolapitant decreased from 176 hours to 41 hours.(3) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Moderate Cyp3a4 Inducers/Tavapadon

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate inducers of CYP3A4 may induce the metabolism of tavapadon.(1)

CLINICAL EFFECTS: Concurrent or recent use of a moderate inducer of CYP3A4 may result in decreased levels and effectiveness of tavapadon.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: For patients initiating tavapadon who are already taking a moderate CYP3A4 inducer, the following tavapadon titration regimen is recommended: - Days 1 to 4: 0.25 mg twice daily - Days 5 to 8: 0.5 mg twice daily - Days 9 to 12: 0.75 mg twice daily - Days 13 to 16: 1 mg twice daily - Days 17 to 20: 1.5 mg twice daily - Days 21 to 24: 2.25 mg twice daily - Days 25 to 40: 3 mg twice daily - Days 41 and after: 5 mg twice daily If needed, based on clinical response and tolerability, the maintenance dosage may be increased to 5 mg three times a day. If further escalation is needed, the dose may be increased by 5 mg every 15 days administered in divided doses (either twice a day or three times a day), to the maximum recommended daily dosage of 45 mg daily (15 mg three times daily). For patients on tavapadon maintenance dosage who are initiating a moderate CYP3A4 inducer, the following dose modifications are recommended: - Days 1 to 7 of concomitant use: continue the current maintenance dosage of tavapadon (5 mg, 10 mg, or 15 mg once daily) - Day 8 and thereafter during concomitant use: increase the frequency of the maintenance dosage of tavapadon to twice daily. If needed, based on clinical response and tolerability, the maintenance dosage can be increased to three times daily. Upon discontinuation of moderate CYP3A4 inducers, gradually reduce the tavapadon dosage to once daily. Monitor patients for clinical response and tolerability.(1)

DISCUSSION: Concurrent administration of efavirenz (600 mg), a moderate CYP3A4 inducer, with 15 mg tavapadon is predicted to decrease the area-under-the-curve (AUC) and maximum concentration (Cmax) by 70% and 58%.(1) When a moderate CYP3A4 inducer is initiated during maintenance therapy (5, 10, or 15 mg doses) of tavapadon, with increased dosing frequency from once daily to three times daily, steady state AUC and Cmax are not predicted to differ significantly relative to once daily dosing without an inducer.(1) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3)

Pacritinib/Digoxin

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Pacritinib may increase the absorption of digoxin by inhibiting P-glycoprotein (P-gp).(1)

CLINICAL EFFECTS: Concurrent use of Pacritinib may result in elevated levels of and toxicity from digoxin.(1) Symptoms of digoxin toxicity can include anorexia, nausea, vomiting, headache, fatigue, malaise, drowsiness, generalized muscle weakness, disorientation, hallucinations, visual disturbances, and arrhythmias.

PREDISPOSING FACTORS: Low body weight, advanced age, impaired renal function, hypokalemia, hypercalcemia, and/or hypomagnesemia may increase the risk of digoxin toxicity.

PATIENT MANAGEMENT: Monitor digoxin concentrations before initiating concomitant use with pacritinib and continue monitoring serum digoxin concentrations as recommended in the prescribing information for digoxin.(1-2) The manufacturer of digoxin recommends decreasing the dose of digoxin by approximately 15-30% or by modifying the dosing frequency to reduce digoxin concentrations.(2)

DISCUSSION: Pacritinib (200 mg twice daily at steady state) increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of digoxin (0.25 mg) by 29% and 15%, respectively.(1)

Pacritinib/Moderate Cyp3a4 Inhibitors

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Agents that inhibit the CYP3A4 isoenzyme may inhibit the metabolism of pacritinib.(1)

CLINICAL EFFECTS: Concurrent use of moderate CYP3A4 inhibitors may increase levels of and effects from pacritinib.(1) Elevated levels of pacritinib may result in QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP). Other toxicities include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of pacritinib recommends monitoring patients concomitantly receiving moderate CYP3A4 inhibitors (e.g., fluconazole) for increased adverse reactions and considering pacritinib dose modifications based on safety.(1) When concurrent therapy is warranted monitor for prolongation of the QTc interval.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(1)

DISCUSSION: Fluconazole (200 mg once daily for 7 days, a moderate CYP3A4 inhibitor) increased maximum concentration (Cmax) and area-under-curve (AUC) of pacritinib (200 mg twice daily at steady state) by 41% and 45%, respectively.(1) Concomitant use of pacritinib with doses of fluconazole greater than 200 mg once daily have not been studied.(1) Clarithromycin (500 mg twice daily for 5 days, a strong CYP3A4 inhibitor) increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of pacritinib (400 mg) by 80% and 30%, respectively.(1) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Moderate inhibitors of CYP3A4 include: amprenavir, aprepitant, atazanavir, berotralstat, conivaptan, darunavir, diltiazem, fluvoxamine, fosamprenavir, fosnetupitant, imatinib, isavuconazonium, letermovir, netupitant, schisandra, stiripentol, tofisopam, treosulfan, and verapamil.(3,4)

Pacritinib/Moderate Cyp3a4 Inhibitors That Prolong Qt

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate inhibitors of CYP3A4 that prolong the QTc interval may inhibit the metabolism of pacritinib and result in additive risk of QT prolongation.(1)

CLINICAL EFFECTS: Concurrent use of moderate CYP3A4 inhibitors that prolong QT may increase the levels and effects of pacritinib, including additive QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(1) Other toxicities include bleeding, diarrhea, thrombocytopenia, major adverse cardiovascular events, thrombosis, and infection.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of pacritinib recommends monitoring patients concomitantly receiving moderate CYP3A4 inhibitors (e.g., fluconazole) for increased adverse reactions and considering pacritinib dose modifications based on safety.(1) When concurrent therapy is warranted monitor for prolongation of the QTc interval.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose according to labeling.(1)

DISCUSSION: Fluconazole (200 mg once daily for 7 days, a moderate CYP3A4 inhibitor) increased maximum concentration (Cmax) and area-under-curve (AUC) of pacritinib (200 mg twice daily at steady state) by 41% and 45%, respectively.(1) Concomitant use of pacritinib with doses of fluconazole greater than 200 mg once daily have not been studied.(1) In a 24 week clinical study, patients treated with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(5) Moderate inhibitors of CYP3A4 that prolong QT include: dronedarone, erythromycin, fluconazole, and nilotinib.(3,4)

Pacritinib/Possible Qt Prolonging Agents

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Pacritinib has been observed to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of pacritinib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of pacritinib states concurrent use with agents known to prolong the QT interval should be avoided. Avoid the use of pacritinib in patients with a baseline QTc > 480 msec. Correct hypokalemia prior to initiation and during therapy with pacritinib.(1) If patients develop QTc prolongation >500 msec or >60 msec from baseline, hold pacritinib. If QTc prolongation resolves to <=480 msec or to baseline within 1 week, resume pacritinib at the same dose. If time to resolution of the QTc interval takes greater than 1 week to resolve, reduce the pacritinib dose.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a 24 week clinical study, patients treatment with pacritinib 200 mg twice daily had a change in QTc from baseline of 11 msec (90% CI: 5-17).(1) Pacritinib has been associated with QTc interval prolongation. In clinical trials, patients with QTc prolongation >500 msec occurred in 1.4% of patients in the treatment arm compared to 1% in the control arm. The treatment arm had a greater incidence of an increase in QTc > 60 msec from baseline than the control arm (1.9% vs 1%, respectively). QTc prolongation adverse reactions were higher in the treatment arm than the control group (3.8% vs 2%, respectively).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3)

Pacritinib/Rosuvastatin (<= 20 Mg)

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Pacritinib is an inhibitor of the BCRP transporter, which may result in increased absorption and decreased hepatic uptake of rosuvastatin.(1-3)

CLINICAL EFFECTS: Concurrent use of pacritinib with rosuvastatin may result in increased levels and side effects from rosuvastatin, including myopathy and rhabdomyolysis.(1-2)

PREDISPOSING FACTORS: The risk for myopathy or rhabdomyolysis may be greater in patients 65 years and older, inadequately treated hypothyroidism, renal impairment, carnitine deficiency, malignant hyperthermia, or in patients with a history of myopathy or rhabdomyolysis. Patients with a SLCO1B1 polymorphism that leads to decreased function of the hepatic uptake transporter OATP1B1 may have increased statin concentrations and be predisposed to myopathy or rhabdomyolysis. Patients on rosuvastatin with ABCG2 polymorphisms leading to decreased or poor BCRP transporter function may have increased rosuvastatin concentrations and risk of myopathy.

PATIENT MANAGEMENT: The manufacturer of pacritinib states that the dose of rosuvastatin should not exceed 20 mg daily when used concurrently.(1) Monitor patients closely for signs and symptoms of toxicity from increased rosuvastatin concentrations.(1,2)

DISCUSSION: Concurrent use of pacritinib (200 mg twice daily at steady state) increased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of rosuvastatin (5 mg) by 200% and 80%, respectively.(1)

Pacritinib/Ubrogepant

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Pacritinib is a moderate CYP3A4 inducer and a BCRP inhibitor.(1) Ubrogepant is a CYP3A4 and BCRP substrate.(2,3) Pacritinib may induce the metabolism and increase the absorption of ubrogepant.(1,2)

CLINICAL EFFECTS: The net effect of this interaction is unknown. Concurrent use of moderate CYP3A4 inducers with ubrogepant may result in decreased levels and effectiveness of ubrogepant while concurrent use of agents that inhibit BCRP may result in elevated levels and side effects from ubrogepant.(1,2)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The effect of CYP3A4 induction and BCRP inhibition on ubrogepant is unknown. The optimal dose of ubrogepant when used concurrently with pacritinib has not been determined. Without guidance on managing these opposing effects, concurrent use cannot be recommended. Dose modifications mentioned below are informational only. The manufacturer of pacritinib states CYP3A4 and BCRP substrates should be monitored and dose adjusted when used concurrently.(1) The manufacturer of ubrogepant does not have recommendations for concurrent use with agents that are both moderate CYP3A4 inducers and BCRP inhibitors.(2) If coadministration with moderate CYP3A4 inducers cannot be avoided, the manufacturer of ubrogepant recommends a dose adjustment of ubrogepant.(2) The dose of ubrogepant should not exceed 100 mg for initial dose. A second dose of ubrogepant should not exceed 100 mg and may be taken at least 2 hours after the initial dose if needed.(2) If coadministration with BCRP inhibitors cannot be avoided, the manufacturer of ubrogepant recommends a dosage adjustment of ubrogepant. The dose of ubrogepant should not exceed 50 mg for initial dose. If a second dose of ubrogepant is needed, the dose should not exceed 50 mg.(2)

DISCUSSION: Ubrogepant is a substrate of CYP3A4 and the BCRP transporter.(2,3) Pacritinib is a moderate CYP3A4 inducer and BCRP inhibitor.(1,3) Coadministration of pacritinib (200 mg twice daily at steady state) with a single dose of oral midazolam (2 mg) (a CYP3A4 substrate) decreased the concentration maximum (Cmax) and area-under-curve (AUC) of midazolam by 60% and 60%, respectively.(1) Coadministration of rosuvastatin 5 mg (BCRP substrate) with pacritinib 200 mg twice daily resulted in a 2-fold and 1.8-fold increase in rosuvastatin Cmax and AUC, respectively.(1) The impact of moderate CYP3A4 inducers on the pharmacokinetics of ubrogepant has not been investigated in clinical studies. Coadministration of ubrogepant with rifampin, a strong CYP3A4 inducer, resulted in an 80% reduction in ubrogepant exposure.(2) Use of P-gp or BCRP inhibitors may increase the exposure of ubrogepant. Clinical drug interaction studies with inhibitors of these transporters were not conducted.(2)

Possible Qt Prolonging Agents/Dexmedetomidine Sublingual

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Dexmedetomidine sublingual has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of dexmedetomidine sublingual with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of dexmedetomidine sublingual states that concurrent use should be avoided with other agents known to prolong the QTc interval.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a QT study, dexmedetomidine sublingual had a concentration dependent effect on the QT interval. The mean QTc (95% confidence interval) increased from baseline by 6 (7) msec with a 120 mcg single dose, 8 (9) msec with 120 mcg followed by 2 additional doses of 60 mcg (total 3 doses), 8 (11) msec with a single 180 mcg dose, and 11 (14) msec with 180 mcg followed by 2 additional doses of 90 mcg (total 3 doses), respectively.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3)

Possible Qt Prolonging Agents/Firmonertinib

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Firmonertinib may prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of firmonertinib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of firmonertinib states that firmonertinib should be avoided in patients with risk factors that may increase the risk of QTc interval prolongation or arrhythmic events, such as heart failure, hypokalemia, or congenital long QT syndrome.(1) Concurrent use of QT prolonging agents should be avoided. If concurrent use cannot be avoided, obtain ECGs prior to initiating firmonertinib, during concomitant use, and as clinically indicated. More frequent ECG monitoring may be necessary. The manufacturer of firmonertinib states patients with at least two independent ECG tests indicating a QTc > 500 ms should temporarily discontinue firmonertinib until QTc < 481 ms or returns to baseline levels (e.g., baseline QTc > or = 481 ms). Patients with QTc prolongation and severe arrhythmic symptoms or signs should permanently discontinue firmonertinib.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In clinical trials, among 446 patients treated with firmonertinib at a dose of 80 mg, 57 (12.8%) experienced QT interval prolongation on an ECG, of which 6 (1.3%) were grade 3 and the rest were grade 1-2. Of these, 7 (1.6%) experienced dose interruption, 5 (1.1%) experienced dose reduction, and 1 (0.2%) experienced permanent discontinuation of treatment.(1) In another study, QTc interval prolongation was reported as an adverse event in 6% of 130 patients (in 20 mg, 40 mg, 80 mg, and 160 mg groups; n=2 each). All were classified as grade 1 or grade 2 and assessed as possibly related to treatment. Two events (grade 2 at 80 mg, grade 2 at 160 mg) led to dose interruption before resolution. QT prolongation in the remaining patients was resolved without intervention, except for one event (grade 1) reported as worsening.(3)

Possible Qt Prolonging Agents/Gadofosveset

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: QT prolongation has been reported following gadofosveset administration. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The use of gadofosveset in patients maintained on agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: In patients maintained on agents known to prolong the QT interval, consider a baseline ECG prior to administration of gadofosveset to asses the risk/benefit of gadofosveset. If gadofosveset is used, consider ECG monitoring for 72 hours until the majority of gadofosveset is eliminated. Consider obtaining serum calcium, magnesium, and potassium levels and correct any electrolyte abnormalities. Counsel patients to report any irregular heartbeat, dizziness, or fainting episodes during this time frame.(1)

DISCUSSION: In clinical trials, 6% of patients experienced an increase in QTc of 30 msec to 60 msec 45 minutes after the administration of gadofosveset and 0.4% of patients experienced a QTc increase of greater than 60 msec at 45 minutes post-administration.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3)

Possible Qt Prolonging Agents/Givinostat

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Givinostat may prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of givinostat with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of givinostat states that the concurrent use of QT prolonging agents should be avoided. If concurrent use cannot be avoided, obtain ECGs prior to initiating givinostat, during concomitant use, and as clinically indicated.(1) If the QTc interval is greater than 500 ms or the change from baseline is greater than 60 ms, withhold givinostat therapy.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a QT study, the largest mean increase in QTc interval of 13.6 ms (upper confidence interval of 17.1 ms) occurred 5 hours after administration of givinostat 265.8 mg (approximately 5 times the recommended 53.2 mg dose in patients weighing 60 kg or more).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3)

Possible Qt Prolonging Agents/Milsaperidone

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Milsaperidone may prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of milsaperidone with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age, and with concurrent use of inhibitors of CYP3A4 or CYP2D6, which metabolize milsaperidone.(1,2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of milsaperidone states that concurrent use of other drugs that are known to prolong the QTc interval should be avoided. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If the QTc interval is consistently above 500 msec, discontinue milsaperidone.(1)

DISCUSSION: Milsaperidone and iloperidone rapidly interconvert in vivo. In a study of 160 patients with psychiatric disorders, coadministration of paroxetine (20 mg daily) and iloperidone (12 mg twice daily) was associated with a mean QTcF increase of 19 msec from baseline, compared with an increase of 9 msec with iloperidone alone.(1) Coadministration of ketoconazole (a CYP3A4 inhibitor) and paroxetine did not increase the effects on iloperidone compared with either agent alone.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3)

Possible Qt Prolonging Agents/Vepdegestrant

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Vepdegestrant may prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of vepdegestrant with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, and advanced age.(1,2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of vepdegestrant states that concurrent use of other drugs that are known to prolong the QTc interval should be avoided. If concurrent therapy is warranted, monitor ECG when initiating vepdegestrant, during concurrent use, and as clinically indicated. Consider increasing the frequency of ECG monitoring. Do not initiate vepdegestrant in patients with a baseline QTc >470 ms. Withhold vepdegestrant if the QTc is >480 ms or the change from baseline is >60 ms.(1) Consider obtaining serum calcium, magnesium, and potassium levels and correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Vepdegestrant 200 mg daily increased QTc by 12 ms (upper confidence interval = 15 ms) in patients with ESR1 mutation-positive breast cancer.(1) In VERITAC-2, QTc prolongation occurred in 10% of patients, with 1.6% of patients having Grade 3 events. QTc was >500 ms in 1.6% of patients and QTc increase from baseline of >60 ms occurred in 2.6% of patients.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3)

Qt Prolonging Agents/Anamorelin

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Anamorelin may prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of anamorelin with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of anamorelin states that the concurrent use of QT prolonging agents should be approached with caution, especially in the early stages (i.e., the first 3 weeks) of drug administration.(1,3) Obtain serum calcium, magnesium, and potassium levels and monitor ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. If abnormalities are found, take appropriate measures, including discontinuing anamorelin.(1) Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Anamorelin blocks sodium channels and may suppress cardiac conduction, resulting in prolongation of the QRS width or QT interval. A study of 7 healthy volunteers receiving single-dose anamorelin 400 mg found that 1 patient experienced QRS width prolongation. In 60 healthy adults recieving anamorelin, the maximum difference (upper limit of 95% one-sided confidence interval) in the change from baseline in QTcF interval compared to placebo was 6.16 (7.73) msec in patients on 100 mg and 7.38 (10.31) msec in patients on 300 mg.(1) The Japanese pharmacovigilance database was reviewed to evaluate disproportionality of conduction defects related to anamorelin. Out of 537 cases of adverse reactions, there were 51 cases of conduction defects (36 cases of prolonged QT, 5 cases of prolonged QRS complex, 2 cases of long QT syndrome). When adjusted for concomitant use of QT prolonging agents, the reporting odds ratio (ROR) of anamorelin-related conduction defects was 20.00 (95% CI 14.86-26.91).(3) There have been several case reports of widened QRS complexes following anamorelin exposure, usually accompanied by worsening hepatic function.(4-6) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(7)

Qt Prolonging Agents/Catequentinib

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Catequentinib has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of catequentinib with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes (TdP).(1)

PREDISPOSING FACTORS: In general, the risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The concurrent use of catequentinib with other agents known to prolong the QTc interval should be monitored closely. Monitor ECG and electrolytes regularly (every 3-6 weeks) if catequentinib is administered with concurrent QTc prolonging drugs.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Catequentinib causes QTc prolongation. In clinical studies, QTc prolongation was reported as a very common adverse effect.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3)

Qt Prolonging Agents/Gepirone

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Gepirone has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of gepirone with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of gepirone states that gepirone should be used with caution and ECGs should be monitored more frequently when used with other agents known to prolong the QTc interval.(1) If QTcF is > 450 msec at baseline, do not initiate gepirone. If QTc increases to > 450 msec during treatment, monitor ECGs more frequently and do not increase the dose of gepirone.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a thorough QT study, 100 mg per day of immediate-release gepirone increased the mean QTc 18.4 msec (upper 90% CI = 22.7 msec) on day 1 and 16.1 msec (upper 90% CI = 20.7) on day 7. The dose of gepirone was 2-fold the exposure of the recommended maximum daily dose.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3)

Qt Prolonging Agents/Mavorixafor

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Mavorixafor has been shown to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The concurrent use of mavorixafor with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The manufacturer of mavorixafor states that concurrent use of mavorixafor with other agents known to prolong the QTc interval should be approached with caution. ECG monitoring is recommended prior to initiation, during concurrent therapy, and as clinically indicated with other agents known to prolong the QTc interval.(1) If QT prolongation occurs, a dose reduction or discontinuation of mavorixafor may be required.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a thorough QT study, a dose of mavorixafor 800 mg increased the mean QTc 15.6 msec (upper 90% CI = 19.9 msec). The dose of mavorixafor was 2 times the recommended maximum daily dose.(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or torsades de pointes in clinical trials and/or postmarketing reports.(3)

Qt Prolonging Agents/Triclabendazole

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Triclabendazole has been observed to prolong the QTc interval. Concurrent use with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1) Triclabendazole is partially metabolized by CYP1A2. Ciprofloxacin, propafenone, and vemurafenib are CYP1A2 inhibitors and may inhibit the CYP1A2 mediated metabolism of triclabendazole.

CLINICAL EFFECTS: The concurrent use of triclabendazole with other agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Hepatic impairment and concurrent use of CYP1A2 inhibitors may raise triclabendazole levels and increase the risk of QT prolongation.(1)

PATIENT MANAGEMENT: The manufacturer of triclabendazole states concurrent use with agents known to prolong the QT interval should be used with caution. Monitor ECG in patients with a history of QTc prolongation, symptoms of long QT interval, electrolyte imbalances, concurrent CYP1A2 inhibitors, or hepatic impairment. If signs of a cardiac arrhythmia develop, stop treatment with triclabendazole and monitor ECG.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a thorough QT study, a dose-dependent prolongation in the QTc interval was observed with triclabendazole. The largest placebo-corrected mean increase in QTc was 9.2 msec (upper limit of confidence interval (UCI): 12.2 msec) following oral administration of 10 mg/kg triclabendazole twice daily (at the recommended dose), and the largest placebo-corrected mean increase in QTc was 21.7 msec (UCI: 24.7 msec) following oral administration of 10 mg/kg triclabendazole twice daily for 3 days (3 times the approved recommended dosing duration).(1) Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3)

Qt Prolonging Agents/Tucidinostat

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Concurrent use of tucidinostat with other agents that prolong the QTc interval may result in additive effects on the QTc interval.(1)

CLINICAL EFFECTS: The use of tucidinostat in patients maintained on agents that prolong the QTc interval may result in potentially life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: Concurrent use of tucidinostat and other agents that are known to prolong the QTc interval should be used with caution. The manufacturer of tucidinostat recommends monitoring ECG and electrolytes every three weeks.(1) If the QTc interval exceeds 500 ms, tucidinostat should be suspended and the ECG should be monitored more frequently. After the QTc interval prolongation has resolved, tucidinostat may be restarted at a reduced dose.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Agents that are linked to this monograph may have varying degrees of potential to prolong the QTc interval but are generally accepted to have a risk of causing Torsades de Pointes. Agents linked to this monograph have been shown to prolong the QTc interval either through their mechanism of action, through studies on their effects on the QTc interval, or through reports of QTc prolongation and/or Torsades de Pointes in clinical trials and/or post-marketing reports.(3)

Select Moderate Cyp3a4 Inducer/Emtricitabine-Rilpivirine-Taf

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may induce the metabolism of rilpivirine.(1-2)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may result in decreased levels and effectiveness of rilpivirine, as well as the development of resistance.(1-2)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US DHHS HIV guidelines state that concurrent use of bosentan or mavacamten (moderate CYP3A4 inducers) with oral rilpivirine should be monitored closely. Consider alternative therapies that do not affect CYP3A4 or alternative antiretroviral agents. If concurrent use is necessary, virologic response should be monitored.(3) The US manufacturer of oral rilpivirine states that concurrent use of rifabutin (moderate CYP3A4 inducer) warrants dose adjustment. When administering moderate CYP3A4 inducers with oral rilpivirine, increase the dose of rilpivirine to 50 mg once daily. When rifabutin co-administration is stopped, the rilpivirine dose should be decreased to 25 mg once daily. It may take several weeks after the discontinuation of an enzyme inducer for enzyme activity to return to normal.(2)

DISCUSSION: In a study in 18 subjects, rifabutin (300 mg daily) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of rilpivirine (25 mg orally daily) by 31%, 42%, and 48%, respectively.(1) A study in 18 subjects compared rilpivirine administered alone (25 mg orally daily) to coadministration with rifabutin (300 mg daily) and rilpivirine (50 mg orally daily). A significant difference was not found with the Cmax (1.43), AUC (1.16), or Cmin (0.93) of rilpivirine. (2) Selected moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, elagolix, eslicarbazepine, fexinidazole, lesinurad, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat, thioridazine and tovorafenib.(3)

Selected Bcrp Inhibitors/Atorvastatin

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Atorvastatin is a substrate of the BCRP transporter.(1) Inhibitors of this transporter may increase intestinal absorption and hepatic uptake of BCRP substrates atorvastatin.(1)

CLINICAL EFFECTS: Administration of atorvastatin with BCRP inhibitors may result in elevated levels of atorvastatin, which could result in rhabdomyolysis.(1)

PREDISPOSING FACTORS: The risk for myopathy or rhabdomyolysis may be greater in patients 65 years and older, inadequately treated hypothyroidism, renal impairment, carnitine deficiency, malignant hyperthermia, or in patients with a history of myopathy or rhabdomyolysis. Patients with a SLCO1B1 polymorphism that leads to decreased function of the hepatic uptake transporter OATP1B1 may have increased statin concentrations and be predisposed to myopathy or rhabdomyolysis.

PATIENT MANAGEMENT: Concurrent use of atorvastatin with BCRP inhibitors may result in increased risk of side effects associated with atorvastatin. Close monitoring would be prudent for statin related side effects including rhabdomyolysis. If concurrent therapy is deemed medically necessary, monitor patients for signs and symptoms of myopathy/rhabdomyolysis, including muscle pain/tenderness/weakness, fever, unusual tiredness, changes in the amount of urine, and/or discolored urine.

DISCUSSION: Atorvastatin is a BCRP substrate.(1) BCRP inhibitors linked to this monograph include: capmatinib, clopidogrel, curcumin, danicopan, encorafenib, fostamatinib, lazertinib, leflunomide, momelotinib, oteseconazole, pacritinib, pirtobrutinib, regorafenib, ritonavir, rolapitant, roxadustat, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tafamidis, teriflunomide, tolvaptan, turmeric, vadadustat, velpatasvir, and zongertinib.(2,3)

Selected Moderate Cyp3a4 Inducers/Rilpivirine

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Moderate CYP3A4 inducers may induce the metabolism of rilpivirine.(1)

CLINICAL EFFECTS: Concurrent or recent use of moderate CYP3A4 inducers may result in decreased levels and effectiveness of rilpivirine, as well as the development of resistance.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US DHHS HIV guidelines state that concurrent use of bosentan or mavacamten (moderate CYP3A4 inducers) with oral or intramuscular rilpivirine should be monitored closely. Consider alternative therapies that do not affect CYP3A4 or alternative antiretroviral agents. If concurrent use is necessary, virologic response should be monitored.(2) The US manufacturer of oral rilpivirine states that concurrent use of rifabutin (moderate CYP3A4 inducer) warrants dose adjustment. When administering moderate CYP3A4 inducers with oral rilpivirine, increase the dose of rilpivirine to 50 mg once daily. When rifabutin co-administration is stopped, the rilpivirine dose should be decreased to 25 mg once daily. It may take several weeks after the discontinuation of an enzyme inducer for enzyme activity to return to normal.(1)

DISCUSSION: In a study in 18 subjects, rifabutin (300 mg daily) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of rilpivirine (25 mg orally daily) by 31%, 42%, and 48%, respectively.(1) A study in 18 subjects compared rilpivirine administered alone (25 mg orally daily) to coadministration with rifabutin (300 mg daily) and rilpivirine (50 mg orally daily). A significant difference was not found with the Cmax (1.43), AUC (1.16), or Cmin (0.93) of rilpivirine. (1) Selected moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, elagolix, eslicarbazepine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, sotorasib, telotristat, thioridazine and tovorafenib.(3)

Selected Moderate-Weak Cyp3a4 Inducers/Exemestane

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: CYP3A4 inducers may induce the metabolism of exemestane.(1)

CLINICAL EFFECTS: Concurrent use of a CYP3A4 inducer may result in decreased levels and effectiveness of exemestane.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The US manufacturer of exemestane recommends that patients receiving concurrent therapy with a strong CYP3A4 inducer receive 50 mg of exemestane daily after a meal.(1) It may be prudent to consider a dosage increase for patients receiving weaker CYP3A4 inducers.

DISCUSSION: In a study in 10 healthy postmenopausal subjects, pretreatment with rifampin (a strong CYP3A4 inducer, 600 mg daily for 14 days) decreased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of exemestane (25 mg) by 54% and 41%, respectively.(1) Strong inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 80% or more and include: carbamazepine, enzalutamide, mitotane, phenobarbital, phenytoin, rifabutin, rifampin, and St. John's wort.(1-3) Moderate inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 50-80% and include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(2,3) Weak inducers of CYP3A4 would be expected to decrease the AUC of a sensitive 3A4 substrate by 20-50% and include: armodafinil, aumolertinib, bexarotene, brigatinib, brivaracetam, clobazam, danshen, darolutamide, dexamethasone, dicloxacillin, echinacea, elafibranor, enasidenib, eslicarbazepine, floxacillin, garlic, gingko, ginseng, glycyrrhizin, lorlatinib, meropenem-vaborbactam, methylprednisolone, nevirapine, omaveloxolone, oritavancin, oxcarbazepine, pioglitazone, pitolisant, quercetin, relugolix, rufinamide, sarilumab, sulfinpyrazone, sunvozertinib, suzetrigine, tazemetostat, tecovirimat, terbinafine, ticlopidine, topiramate, troglitazone, vemurafenib, vinblastine, and zanubrutinib.(2,3)

Slt 2C19&3A4 Inducer That Prolong Qt/Citalopram;Escitalopram

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Dual CYP2C19 and CYP3A4 inducers that prolong the QTc interval may induce the metabolism of citalopram and escitalopram and result in additive risk of QT prolongation.(1,2)

CLINICAL EFFECTS: Concurrent use of dual CYP2C19 and CYP3A4 inducers that prolong QT may decrease systemic levels and effectiveness of citalopram and escitalopram and may cause additive effects on the QTc interval, which may result in life-threatening cardiac arrhythmias including torsades de pointes.(1,2)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: When used concomitantly with CYP2C19 and CYP3A4 inducers, monitoring of concentrations or dosage adjustment of citalopram may be necessary.(1) Concurrent use of citalopram with agents known to prolong the QT interval should be avoided.(1) Due to the risk of QT prolongation, citalopram doses greater than 40 mg once daily are not recommended. Citalopram doses should be limited to 20 mg once daily in patients who are CYP2C19 poor metabolizers or patients receiving CYP2C19 inhibitors.(1) If patients have a persistent QTc measurement > 500 ms, discontinue citalopram. If a patient develops symptoms including dizziness, palpitations, or syncope, further evaluation is warranted included cardiac monitoring.(1) While the US FDA and manufacturer recommend no special precautions when escitalopram is used with QT prolonging agents,(3,4) Health Canada and the Canadian manufacturer of escitalopram discourage the concurrent use of agents known to prolong the QT interval(5,6) and the UK manufacturer states that concurrent use is contraindicated.(7) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Citalopram has been associated with dose-depended increases in the QTc interval. In healthy subjects, the maximum mean difference in QTc interval seen with 20 mg of citalopram and 60 mg of citalopram were 8.5 msec (90% CI = 6.2-10.8 msec) and 18.5 msec (90% CI = 16.0-21.0 msec), respectively. Based on extrapolation, a 40 mg dose of citalopram is expected to produce a mean increase in the QTc interval of 12.6 msec (90% CI = 10.9-14.3 msec).(1) In a clinical trial of use of citalopram for agitation in Alzheimer's disease, citalopram (30 mg daily) was associated with a mean increase in QTc of 18.1 msec.(8) Combined administration of racemic citalopram (40 mg/day for 14 days) and carbamazepine (a dual CYP3A4 and CYP2C19 inducer) titrated to 400 mg/day for 35 days did not affect citalopram plasma trough levels. Given the enzyme-inducing properties of carbamazepine, the possibility that carbamazepine might increase the clearance of escitalopram should be considered if the two drugs are coadministered.(1,3) A case report of a 55-year-old man receiving citalopram for panic disorder reported a decrease in the agent's therapeutic efficacy when rifampin was started. His condition improved when rifampin was stopped.(9) Dual CYP2C19 and CYP3A4 inducers that prolong QT linked to this monograph include: efavirenz and pacritinib.(10,11)

Strong & Moderate Cyp3a4 Inducers That Prolong Qt/Siponimod

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Drugs that are moderate or strong inducers of CYP3A4 may increase the metabolism of siponimod.(1) Patients with a CYP2C9*1/*3 or *2/*3 genotype who are more dependent on CYP3A4 for the metabolism of siponimod would experience a greater effect of CYP3A4 induction. Initiation of siponimod has a negative chronotropic effect and may cause bradycardia. Concurrent use with CYP3A4 inducers that prolong the QT interval may increase the risk of bradycardia and QT prolongation.(1,2)

CLINICAL EFFECTS: Concurrent use of a siponimod with a moderate or strong CYP3A4 inducer in patients with a CYP2C9*1/*3 or *2/*3 genotype may result in decreased levels and effectiveness of siponimod.(1) The heart rate lowering effect of siponimod starts within an hour, and the Day 1 decline is maximal at approximately 3-4 hours. This leads to a mean decrease in heart rate of 5-6 beats per minute after the first dose. The first dose has also been associated with heart block. With continued up-titration, further heart rate decreases are seen on subsequent days, with maximal decrease from Day 1-baseline reached on Day 5-6. Symptomatic bradycardia has been observed. Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsades de pointes.(1,2)

PREDISPOSING FACTORS: Patients with a CYP2C9*1/*3 or *2/*3 genotype who are more dependent on CYP3A4 for the metabolism of siponimod would experience a greater effect of CYP3A4 induction. Pre-existing cardiovascular or cerebrovascular disease (e.g. heart failure, ischemic heart disease, history of myocardial infarction, stroke, or heart block), severe untreated sleep apnea, a prolonged QTc interval prior to siponimod initiation, factors associated with QTc prolongation (e.g. hypokalemia, hypomagnesemia), or concomitant treatment with QT prolonging agents may increase risk for cardiovascular toxicity due to siponimod. The risk of QT prolongation or torsades de pointes may also be increased in patients with a history of torsades de pointes, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of the QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Monitor the combination of siponimod with a moderate or strong CYP3A4 inducer in patients with a CYP2C9*1/*3 or *2/*3 genotype for loss of efficacy.(1) Agents that are both moderate CYP3A4 inducers and moderate CYP2C9 inducers (e.g., lorlatinib) should be used with caution regardless of the patient's CYP2C9 genotype.(1) Patients receiving concurrent treatment with a QT prolonging agent at the time siponimod is initiated or resumed should be referred to a cardiologist. Consult the prescribing information for recommendations regarding cardiac monitoring.(1)

DISCUSSION: In a study, efavirenz (a moderate CYP3A4 inducer) decreased the area-under-curve (AUC) of siponimod by up to 52% across CYP2C9 genotypes. After the first dose of siponimod, heart rate decrease may begin within an hour. Decline is usually maximal at approximately 3-4 hours. With continued, chronic dosing, heart rate gradually returns to baseline in about 10 days.(1,2) A transient, dose-dependent decrease in heart rate was observed during the initial dosing phase of siponimod, which plateaued at doses greater than or equal to 5 mg, and bradyarrhythmic events (AV blocks and sinus pauses) were detected at a higher incidence under siponimod treatment than placebo. AV blocks and sinus pauses occurred above the recommended dose of 2 mg, with notably higher incidence under non-titrated conditions compared to dose titration conditions.(1) Drugs that are moderate or strong CYP3A4 inducers linked to this monograph include: efavirenz, ivosidenib, pacritinib and thioridazine.(4,5)

Strong & Moderate Cyp3a4 Inducers/Apixaban; Rivaroxaban

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Apixaban and rivaroxaban are both substrates of CYP3A4 and P-glycoprotein (P-gp). Apixaban is about 20% metabolized and rivaroxaban is about 18% metabolized, mainly by CYP3A4.(1-8) Strong and moderate CYP3A4 inducers may induce the metabolism of apixaban and rivaroxaban by CYP3A4.

CLINICAL EFFECTS: Concurrent or recent use of a CYP3A4 inducer may result in decreased levels and effectiveness of apixaban(1-4) or rivaroxaban,(5-8) especially in the setting of concurrent therapy with an agent that induces P-gp.

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks. Drug-associated risk factors include concurrent use of P-gp inducers.

PATIENT MANAGEMENT: The US, Australian, Canadian, and UK manufacturers of apixaban provide recommendations regarding concurrent use with strong inducers of both CYP3A4 and P-gp, but do not provide guidance for concurrent use with agents that induce CYP3A4 alone.(1) The US manufacturer of rivaroxaban provides recommendations regarding concurrent use with strong inducers of both CYP3A4 and P-gp, but does not provide guidance for concurrent use with agents that induce CYP3A4 alone.(5) The Australian manufacturer of rivaroxaban states that concurrent use of strong CYP3A4 inducers should be approached with caution.(6) The Canadian and UK labels for rivaroxaban state that concurrent use of strong CYP3A4 inducers should be avoided.(7-8) When considering concurrent therapy with a strong or moderate CYP3A4 inducer with either apixaban or rivaroxaban, evaluate the patient's other concurrent therapy for CYP3A4 and P-gp effects. In patients who are taking strong CYP3A4 inducers and are also on concurrent P-gp inducers, consider the manufacturer recommendations for use with dual CYP3A4 and P-gp inducers. The US manufacturers of apixaban and rivaroxaban both state to avoid the concurrent use of agents that are combined P-gp and strong CYP3A4 inducers in patients receiving apixaban or rivaroxaban.(1-8) In patients who are taking moderate CYP3A4 inducers and are also on concurrent P-gp inducers, it may be prudent to consider alternative therapy or monitor the patient closely. For patients taking efavirenz or etravirine, the US and European HIV guidelines recommend considering alternative therapies or performing additional monitoring.(9-10)

DISCUSSION: The concurrent use of apixaban or rivaroxaban with strong CYP3A4 inducers that are not also P-gp inducers has not been studied. Apixaban and rivaroxaban are metabolized primarily by CYP3A4. Strong CYP3A4 inducers may decrease the levels and effectiveness of apixaban and rivaroxaban. The US manufacturer of apixaban states that apixaban dose reduction is recommended when apixaban exposure increases by more than 50%, while efficacy is maintained when exposure is 25% lower. Therefore, no dose adjustment of apixaban is recommended for drug interactions that affect apixaban exposure by 75% to 150%.(11) An article evaluating the clinical significance of efflux transporters like P-gp and BCRP in apixaban exposure analyzed pharmacokinetic data from drug-drug interaction studies and concluded that all apixaban interactions can be explained by inhibition of intestinal CYP3A4. The authors explain that apixaban is a highly permeable and soluble compound, so its ability to undergo passive diffusion renders the role of membrane transporters irrelevant, as evidenced by a lack of change in apixaban absorption rate in the presence of drugs known to inhibit P-gp and BCRP.(12) Strong CYP3A4 inducers linked to this monograph include: barbiturates, encorafenib, ivosidenib, lumacaftor, and mitotane.(13,14) Moderate CYP3A4 inducers linked to this monograph include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat ethyl, thioridazine, and tovorafenib.(13,14)

Strong And Moderate Cyp3a4 Inducers/Perampanel

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may induce the metabolism of perampanel by CYP3A4.(1)

CLINICAL EFFECTS: The concurrent use of strong and moderate CYP3A4 inducers and perampanel may result in decreased levels and clinical effectiveness of perampanel.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Patients receiving concurrent therapy with strong and moderate CYP3A4 inducers and perampanel should be observed for decreased anticonvulsant levels and clinical effectiveness. The manufacturer of perampanel recommends a starting dose of 4 mg once daily at bedtime in patients receiving concurrent therapy with CYP3A4 inducers. Dose increases are recommended by 2 mg increments once daily based on clinical response and tolerability, no more frequently than at weekly intervals. The highest studied dose with concurrent enzyme-inducing antiepileptic drugs was 12 mg once daily.(1) The dose of the anticonvulsant may need to be adjusted if a strong or moderate CYP3A4 inducer is added to or removed from therapy.(1)

DISCUSSION: In a study in healthy subjects, carbamazepine 300 mg BID decreased the maximum concentration (Cmax) and area-under-curve (AUC) of a single 2 mg tablet dose of perampanel by 26% and 67%, respectively. The half-life (t1/2) of perampanel was shortened from 56.8 hours to 25 hours. In clinical studies examining partial-onset and primary generalized tonic-clonic seizures, a population pharmacokinetic analysis showed that perampanel AUC was reduced by 64% in patients on carbamazepine compared to the AUC in patients not on enzyme-inducing antiepileptic drugs.(1) In a study in partial-onset and primary generalized tonic-clonic seizures, a population pharmacokinetic analysis showed that perampanel AUC was reduced by 48% in patients on oxcarbazepine compared to patients not on enzyme-inducing antiepileptic drugs.(1) In a study in partial-onset and primary generalized tonic-clonic seizures, a population pharmacokinetic analysis showed that perampanel AUC was reduced by 43% in patients on phenytoin compared to patients not on enzyme-inducing antiepileptic drugs.(1) In a study in partial-onset and primary generalized tonic-clonic seizures in clinical trials (40 patients co-administered phenobarbital and 9 patients co-administered primidone), no significant effect on perampanel AUC was found. A modest effect of phenobarbital and primidone on perampanel concentrations cannot be excluded.(1) In a study in 76 patients, concentration-to-dose (CD) ratio of perampanel was assessed with and without concurrent antiepileptic agents. In patients only on perampanel the mean CD ratio was 3963 ng/mL/mg/kg (range: 1793-13,299) compared to the mean CD ratio in patients using enzyme-inducing AEDs [1760 (range: 892-3090), 2256 (range: 700-4703), and 1120 (range: 473-1853) ng/mL/mg/kg in patients taking phenytoin, phenobarbital, and carbamazepine, respectively], and carbamazepine had a significantly greater reduction in the CD ratio compared with phenytoin or phenobarbital (P < 0.001).(3) Strong and moderate CYP3A4 inducers linked to this monograph include: apalutamide, barbiturates, bosentan, carbamazepine, cenobamate, dabrafenib, efavirenz, elagolix, encorafenib, enzalutamide, eslicarbazepine, etravirine, fexinidazole, fosphenytoin, ivosidenib, lorlatinib, lumacaftor, mavacamten, mitapivat, mitotane, modafinil, nafcillin, oxcarbazepine, pacritinib, pexidartinib, phenobarbital, phenytoin, primidone, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(1,2)

Strong And Moderate Cyp3a4 Inducers/Sildenafil (Pah)

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Sildenafil is metabolized by CYP3A4. Strong and moderate inducers of CYP3A4 may increase the metabolism of sildenafil.(1)

CLINICAL EFFECTS: Concurrent use of a strong or moderate inducer of CYP3A4 may result in substantially decreased levels and effectiveness of sildenafil.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Concomitant use of sildenafil with strong or moderate CYP3A4 inducers should be monitored closely. An increased dosage of sildenafil may be needed. Reduce sildenafil dose to 20 mg three times daily when discontinuing treatment with strong and moderate CYP3A4 inducers.(1)

DISCUSSION: Population pharmacokinetic analysis of data from patients in clinical trials found that sildenafil clearance increased about 3-fold when coadministered with mild CYP3A4 inducers.(1) A randomized, double-blind, placebo-controlled, parallel-group study of 55 healthy volunteers found that 10 days of bosentan (125 mg twice daily), a moderate CYP3A4 inducer, decreased the maximum concentration (Cmax) and area-under-curve (AUC) of sildenafil by 55.4% and 62.6%, respectively. Sildenafil increased bosentan Cmax and AUC by 42% and 49.8%, respectively. The combination was well tolerated without serious adverse events.(2) In a study of 15 HIV-negative subjects, etravirine (800 mg twice daily for 14 days), a moderate CYP3A4 inducer, decreased the Cmax and AUC of sildenafil by 45% and 57%, respectively.(3) The authors of a review article on drug interactions in pulmonary arterial hypertension therapy state that phenytoin and rifampin (strong CYP3A4 inducers) are not recommended with sildenafil due to an expected near-complete clearance of sildenafil.(4) Strong inducers of CYP3A4 include: apalutamide, barbiturates, carbamazepine, encorafenib, enzalutamide, fosphenytoin, ivosidenib, lumacaftor, mitotane, phenobarbital, phenytoin, primidone, rifampin, rifapentine, and St. John's wort.(5,6) Moderate inducers of CYP3A4 include: belzutifan, bosentan, cenobamate, dabrafenib, dipyrone, efavirenz, elagolix, etravirine, fexinidazole, lesinurad, lorlatinib, mavacamten, mitapivat, modafinil, nafcillin, pacritinib, pexidartinib, repotrectinib, rifabutin, sotorasib, telotristat, thioridazine, and tovorafenib.(5,6)

*Concomitant use of strong cytochrome P-450 (CYP) 3A4 inhibitors or inducers.

• Chronic kidney disease stage 4 (severe) GFR 15-29 ml/min
• Chronic kidney disease stage 5 (failure) GFr<15 ml/min
• Lactation

• Atherosclerotic cardiovascular disease
• Child-pugh class C hepatic impairment
• Congenital long QT syndrome
• Diarrhea
• Disease of liver
• Hemorrhage
• Hypokalemia
• Infection
• Kidney disease with likely reduction in glomerular filtration rate (GFr)
• Malignancy
• Malignant lymphoma
• Pregnancy
• Thrombocytopenic disorder
• Thrombotic disorder

There are no moderate contraindications for this drug.

Adverse effects reported in >=20% of patients include diarrhea, thrombocytopenia, nausea, anemia, and peripheral edema.

More Frequent

• Anemia
• Thrombocytopenic disorder

Less Frequent

• Heart failure
• Hemorrhage
• Neutropenic disorder
• Pneumonia

Rare or Very Rare

• Hypoglycemic disorder
• Prolonged QT interval

More Frequent

• Diarrhea
• Nausea
• Peripheral edema

Less Frequent

• Conjunctival hemorrhage
• Cough
• Dizziness
• Dyspnea
• Epistaxis
• Fever
• Pruritus of skin
• Squamous cell carcinoma of skin
• Upper respiratory infection
• Vomiting

Rare or Very Rare

• Skin rash

No enhanced messaging available.

Safety and efficacy of pacritinib have not been established in pediatric patients.

There are no available data on pacritinib use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.

Maternal toxicity and embryonic and fetal loss have been observed in animal studies when pacritinib was administered to pregnant mice or rabbits at dosages considerably lower than the recommended human dose. Advise pregnant women of the potential risk to a fetus. Consider the benefits and risks of pacritinib for the mother and possible risks to the fetus when prescribing pacritinib to a pregnant woman.

There are no data on the presence of pacritinib in either human or animal milk, the effects on the breast-fed child, or the effects on milk production. Because of the potential for serious adverse reactions in the breast-fed child, advise patients that breast-feeding is not recommended during treatment with pacritinib, and for 2 weeks after the last dose.

The manufacturer makes no specific dosage recommendations for geriatric patients.

Clinical studies of pacritinib did not include sufficient numbers of subjects >=65 years of age to determine whether they respond differently from younger subjects.