Nerlynx (neratinib maleate)

Dosage of neratinib maleate is expressed in terms of neratinib.

Dosage interruption and/or reduction or discontinuance of neratinib therapy may be necessary based on severity of adverse reactions. Dosage adjustment of neratinib is recommended based on individual safety and tolerability.

Discontinue neratinib in patients with persistent grade 2 or greater adverse effects that do not recover to grade 0-1 or baseline and patients with any toxicity that requires a treatment delay of greater than 3 weeks; discontinuance of therapy is also recommended in those who cannot tolerate a dosage of 120 mg daily.

Neratinib maleate is administered orally with food. The drug should be taken at approximately the same time each day.

Neratinib tablets should be swallowed whole; tablets should not be chewed, crushed, or split.

Store neratinib tablets at a controlled room temperature of 20-25degreesC (excursions permitted between 15-30degreesC).

No dosing information is available for this tab.

Neratinib is primarily metabolized by cytochrome P-450 (CYP) isoenzyme 3A4 and, to a lesser extent, by flavin-containing monooxygenase (FMO).

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

Neratinib/Ritonavir

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: Ritonavir, a strong inhibitor of CYP3A4, may inhibit the metabolism of neratinib.(1)

CLINICAL EFFECTS: Concurrent use of CYP3A4 inhibitors may result in increased systemic exposure to and effects from neratinib. Life-threatening reactions, such as hepatotoxicity, may occur.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The UK manufacturer of ritonavir states that concurrent use of neratinib with ritonavir is contraindicated.(1) The US manufacturer of ritonavir recommends avoiding concurrent use of neratinib with ritonavir.(2) If concurrent use is warranted, monitor patients closely for increased incidence and severity of diarrhea, abdominal pain, nausea, vomiting, and dehydration.

DISCUSSION: Ketoconazole (400 mg daily for 5 days), a strong CYP3A4 inhibitor, increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of neratinib by 321% and 481%, respectively.(2)

Neratinib/Strong And Moderate 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: 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)

Neratinib/Vonoprazan-Clarithromycin

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: The solubility of neratinib is pH dependent. Changes in gastric pH from proton pump inhibitors (PPIs) may decrease the absorption of neratinib. Vonoprazan is a PPI.(1) If neratinib is absorbed, inhibitors of CYP3A4 may inhibit the metabolism of neratinib. Clarithromycin is a strong CYP3A4 inhibitor.(1)

CLINICAL EFFECTS: Use of proton pump inhibitors may result in decreased levels and effectiveness of neratinib.(1) If neratinib is absorbed, concurrent use of strong CYP3A4 inhibitors may result in increased systemic exposure to and effects from neratinib.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid the use of proton pump inhibitors (PPIs) in patients receiving treatment with neratinib.(1) Consider the use of short-acting antacids in these patients. If antacids are used, separate the administration times by at least 3 hours for neratinib.(1) If H2 antagonist therapy is required, neratinib must be given 10 hours after the H2 blocker and at least 2 hours before the next dose of the H2 blocker.(1) The manufacturer of neratinib also recommends avoiding the concurrent use of neratinib with strong CYP3A4 inhibitors or moderate CYP3A4 and P-gp dual inhibitors.(1) If concurrent use is warranted, monitor patients closely for increased incidence and severity of diarrhea, abdominal pain, nausea, vomiting, and dehydration.

DISCUSSION: In a study in 15 healthy subjects, lansoprazole (30 mg at steady state) decreased the Cmax and AUC of a single dose of neratinib (240 mg) by 71% and 65%, respectively.(1) Ketoconazole (400 mg daily for 5 days), a strong CYP3A4 inhibitor, increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of neratinib by 221% and 381%, respectively.(1) Pharmacokinetic models predicted that verapamil, a moderate CYP3A4 and P-gp dual inhibitor, would increase the Cmax and AUC of neratinib by 203% and 299%, respectively. Fluconazole, a moderate CYP3A4 inhibitor, is not expected to have a significant interaction with neratinib.(1) Strong CYP3A4 inhibitors include: clarithromycin.(1,3)

P-Glycoprotein (P-Gp) Inh/Colchicine (For Cardioprotection)

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: P-glycoprotein (P-gp) inhibitors may affect the transport of colchicine, a P-gp substrate.(1,2)

CLINICAL EFFECTS: Concurrent use of a P-gp inhibitor may result in elevated levels of and toxicity from colchicine. Symptoms of colchicine toxicity include abdominal pain; nausea or vomiting; severe diarrhea; muscle weakness or pain; numbness or tingling in the fingers or toes; myelosuppression; feeling weak or tired; increased infections; and pale or gray color of the lips, tongue, or palms of hands.(1,2)

PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with renal or hepatic impairment.(1,2)

PATIENT MANAGEMENT: The manufacturer of colchicine used for cardiovascular risk reduction states that concurrent use of colchicine with P-gp inhibitors is contraindicated.(1)

DISCUSSION: There are several reports of colchicine toxicity(3-5) and death(6,7) following the addition of clarithromycin to therapy. In a retrospective review of 116 patients who received clarithromycin and colchicine during the same hospitalization, 10.2% (9/88) of patients who received simultaneous therapy died, compared to 3.6% (1/28) of patients who received sequential therapy.(8) An FDA review of 117 colchicine-related deaths that were not attributable to overdose found that 60 deaths (51%) involved concurrent use of clarithromycin.(2) There is one case report of colchicine toxicity with concurrent erythromycin.(9) In a study in 20 subjects, pretreatment with diltiazem (240 mg daily for 7 days) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of colchicine (0.6 mg) by 44.2% (range -46.6% to 318.3%) and by 93.4% (range -30.2% to 338.6%), respectively.(1) In a study in 24 subjects, pretreatment with verapamil (240 mg twice daily for 7 days) increased the Cmax and AUC of a single dose of colchicine (0.6 mg) by 40.1% (range -47.1% to 149.5%) and by 103.3% (range -9.8% to 217.2%), respectively.(1) Colchicine toxicity has been reported with concurrent use of CYP3A4 and P-gp inhibitors such as clarithromycin, cyclosporine, diltiazem, erythromycin, and verapamil.(1,2) P-gp inhibitors include abrocitinib, amiodarone, asciminib, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daraxonrasib, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, imlunestrant, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, valbenazine, velpatasvir, vemurafenib, venetoclax, vepdegestrant, verapamil, vimseltinib, and voclosporin.(1,10,11)

P-Glycoprotein (P-Gp) Inhibitors/Doxorubicin

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: P-glycoprotein (P-gp) inhibition may increase doxorubicin cellular concentration, as well as decrease biliary or renal elimination.(1)

CLINICAL EFFECTS: Increased cellular or systemic levels of doxorubicin may result in doxorubicin toxicity, including cardiomyopathy, myelosuppression, or hepatic impairment.(1)

PREDISPOSING FACTORS: The interaction magnitude may be greater in patients with impaired renal or hepatic function.

PATIENT MANAGEMENT: Avoid the concurrent use of P-gp inhibitors in patients undergoing therapy with doxorubicin.(1) Consider alternatives with no or minimal inhibition. If concurrent therapy is warranted, monitor the patient closely for signs and symptoms of doxorubicin toxicity. For patients on daraxonrasib, the manufacturer of daraxonrasib states that it should be taken at least 4 hours apart from P-gp substrates.(2)

DISCUSSION: Doxorubicin is a substrate of P-gp.(1) Clinical studies have identified and evaluated the concurrent use of doxorubicin and P-gp inhibitors as a target to overcome P-gp mediated multidrug resistance.(3,4) P-gp inhibitors linked to this monograph include: amiodarone, asciminib, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, cimetidine, cyclosporine, daclatasvir, danicopan, daraxonrasib, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo, ginseng, glecaprevir/pibrentasvir, hydroquinidine, imlunestrant, istradefylline, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, paroxetine, pirtobrutinib, propafenone, quercetin, quinidine, quinine, ranolazine, sarecycline, schisandra, selpercatinib, simeprevir, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, tepotinib, valbenazine, vemurafenib, vepdegestrant, verapamil, vimseltinib, and voclosporin.(5,6)

P-Glycoprotein (P-Gp) Inhibitors/Oral Lefamulin

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 P-glycoprotein (P-gp) may increase the absorption of lefamulin.(1) Oral lefamulin tablets may inhibit the metabolism of P-gp inhibitors that are also sensitive CYP3A4 substrates (i.e., asunaprevir, felodipine, ivacaftor, and neratinib).(1-3)

CLINICAL EFFECTS: The concurrent administration of lefamulin with an inhibitor of P-gp may result in elevated levels of lefamulin and signs of toxicity, such as QT prolongation. Coadministration of oral lefamulin with agents that are also sensitive CYP3A4 substrates (i.e., asunaprevir, felodipine, ivacaftor, and neratinib) may result in elevated levels and toxicities of the sensitive CYP3A4 substrate.

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.(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 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).(4)

PATIENT MANAGEMENT: The US manufacturer of lefamulin states that oral lefamulin tablet coadministration with P-gp inhibitors should be avoided.(1) If concomitant therapy with a P-gp inhibitor is necessary, monitor patients closely for prolongation of the QT interval. Obtain serum calcium, magnesium, and potassium levels and monitor ECG at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. Concomitant use of asunaprevir, felodipine, ivacaftor, or neratinib requires close monitoring for adverse effects of these drugs.(1) The manufacturer of venetoclax states that if concurrent use with a P-gp substrate cannot be avoided, take lefamulin at least 6 hours before venetoclax.(5)

DISCUSSION: Coadministration of ketoconazole (a strong CYP3A4 and P-gp inhibitor) with lefamulin tablets increased lefamulin area-under-the-curve (AUC) and maximum concentration (Cmax) by 165% and 58%.(1) In a study, oral lefamulin tablets administered concomitantly with and at 2 or 4 hours before oral midazolam (a CYP3A4 substrate) increased the area-under-curve (AUC) and maximum concentration (Cmax) of midazolam by 200% and 100%, respectively. No clinically significant effect on midazolam pharmacokinetics was observed when co-administered with lefamulin injection.(1) P-gp inhibitors include: asunaprevir, belumosudil, capmatinib, carvedilol, cimetidine, danicopan, daridorexant, diosmin, flibanserin, fluvoxamine, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, ivacaftor, ledipasvir, neratinib, pirtobrutinib, propafenone, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, valbenazine, vimseltinib, and voclosporin.(1-3)

P-Glycoprotein (P-Gp) 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 P-glycoprotein may increase the absorption of topotecan.(1)

CLINICAL EFFECTS: The concurrent administration of topotecan with an inhibitor of P-glycoprotein 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 P-glycoprotein inhibitors should be avoided. If concurrent use is warranted, carefully monitor patients for adverse effects.(1) For patients on daraxonrasib, the manufacturer of daraxonrasib states that it should be taken at least 4 hours apart from P-gp substrates.(2)

DISCUSSION: In clinical studies, the combined use of elacridar (100 mg to 1000 mg) increased the area-under-curve (AUC) of topotecan approximately 2.5-fold.(1) Oral cyclosporine (15 mg/kg) increased the AUC of topotecan lactone and total topotecan to 2-fold to 3-fold of the control group, respectively.(1) P-gp inhibitors linked to this monograph include: adagrasib, amiodarone, asciminib, asunaprevir, aumolertinib, azithromycin, belumosudil, bosutinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, daraxonrasib, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, ginseng, hydroquinidine, imlunestrant, isavuconazonium, itraconazole, ivacaftor, josamycin, ketoconazole, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir/glecaprevir, posaconazole, propafenone, quinidine, ranolazine, selpercatinib, sotorasib, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, vepdegestrant, verapamil, vimseltinib, and voclosporin.(3,4)

P-Gp Inhibitors/Daraxonrasib (>150 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 substrate of P-gp. P-gp inhibitors may inhibit the metabolism of daraxonrasib.(1)

CLINICAL EFFECTS: Concurrent use of P-gp inhibitors may increase the levels and toxicities of daraxonrasib, including dermatologic toxicity, stomatitis, GI perforation, and interstitial lung disease/pneumonitis.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: For patients taking agents that are P-gp inhibitors, reduce the dose of daraxonrasib to 150 mg daily. After the P-gp inhibitor has been discontinued, resume the daraxonrasib dosage taken prior to initiating the inhibitor.(1)

DISCUSSION: In a pharmacokinetic model, quinidine 300 mg three times daily (a P-gp inhibitor) increased the area under curve (AUC) of daraxonrasib by 1.8-fold.(1) P-gp inhibitors include: abrocitinib, amiodarone, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, curcumin, danicopan, daridorexant, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, imlunestrant, ivacaftor, lapatinib, neratinib, osimertinib, pirtobrutinib, propafenone, ranolazine, selpercatinib, tepotinib, tezacaftor, turmeric, valbenazine, velpatasvir, vemurafenib, vepdegestrant, vimseltinib, and voclosporin.(2-3)

P-Gp Or Bcrp Inhibitors/Ubrogepant (> 50 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: Inhibitors of P-glycoprotein (P-gp) or BCRP may increase the absorption of ubrogepant.(1)

CLINICAL EFFECTS: The concurrent administration of ubrogepant with an inhibitor of P-glycoprotein or BCRP may result in elevated levels of ubrogepant.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when coadministered with P-gp or BCRP inhibitors. 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.(1) For patients on concurrent therapy with vimseltinib and ubrogepant: the manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to ubrogepant.(3) For patients on daraxonrasib, the manufacturer of daraxonrasib states that it should be taken at least 4 hours apart from P-gp substrates.(4)

DISCUSSION: Ubrogepant is a substrate of P-gp and BCRP transporters. 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. The US manufacturer of ubrogepant recommends dose adjustment if ubrogepant is coadministered with P-gp or BCRP inhibitors.(1) BCRP inhibitors linked to this monograph include: belumosudil, clopidogrel, curcumin, eltrombopag, febuxostat, fostemsavir, leniolisib, momelotinib, oteseconazole, regorafenib, resmetirom, ritonavir, rolapitant, roxadustat, tafamidis, oral tedizolid, turmeric, vadadustat, and zongertinib.(2,3,5) P-glycoprotein inhibitors linked to this monograph include: asunaprevir, belumosudil, capmatinib, carvedilol, danicopan, daraxonrasib, daridorexant, imlunestrant, neratinib, osimertinib, propafenone, quinidine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, valbenazine, vimseltinib, and voclosporin.(2,3,5)

Select P-Gp Inhibitors/Aumolertinib

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: Aumolertinib is a substrate for P-glycoprotein (P-gp). Inhibitors of P-gp may increase intestinal absorption and decrease elimination of aumolertinib.(1)

CLINICAL EFFECTS: Concurrent use with selected P-gp inhibitors may result in higher systemic concentrations of aumolertinib which may increase the risk for cardiac failure, rhabdomyolysis, thrombosis, elevated LFTs, hyponatremia, hematologic toxicity, and QT prolongation, which may result in potentially life-threatening cardiac arrhythmias like torsade de pointes (TdP).(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) Patients with risk factors for thrombosis may be at higher risk of adverse events, including those with advanced age, obesity (BMI >30), smoking, prolonged immobilization, heart failure, hypercoagulable state, history of venous thromboembolism, malignancy, and major surgery. The risk for 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 rhabdomyolysis.

PATIENT MANAGEMENT: The manufacturer of aumolertinib states concomitant administration of aumolertinib should be avoided with P-gp inhibitors.(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: Based on in vitro data, aumolertinib is a substrate of P-gp.(1) P-gp inhibitors linked to this interaction are: abrocitinib, asunaprevir, belumosudil, capmatinib, carvedilol, cimetidine, cobicistat, conivaptan, curcumin, cyclosporine, danicopan, daridorexant, diltiazem, diosmin, flibanserin, fluvoxamine, fostamatinib, ginseng, glecaprevir/pibrentasvir, grapefruit, imlunestrant, indinavir, isavuconazole, itraconazole, ivacaftor, josamycin, ketoconazole, mifepristone, neratinib, nirmatrelvir, pirtobrutinib, ritonavir, telaprevir, tepotinib, tezacaftor, tipranavir, tucatinib, valbenazine, velpatasvir, verapamil, vimseltinib, voclosporin, and voxilaprevir.(3)

Selected Inhibitors Of P-Gp Or Bcrp/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: Inhibitors of P-glycoprotein (P-gp) or BCRP may increase the absorption of pazopanib.(1)

CLINICAL EFFECTS: The concurrent administration of pazopanib with an inhibitor of P-glycoprotein or BCRP may result in elevated levels of pazopanib and signs of toxicity.(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 P-gp inhibitors or BCRP inhibitors should be avoided.(1) Monitor patients for increased side effects from pazopanib. The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(5) 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: Pazopanib is a substrate of P-gp and BCRP. Inhibitors of these transporters are expected to increase pazopanib levels.(1) BCRP inhibitors linked to this monograph include: asciminib, belumosudil, clopidogrel, cyclosporine, curcumin, darolutamide, eltrombopag, enasidenib, febuxostat, fostemsavir, grazoprevir, lazertinib, leflunomide, leniolisib, momelotinib, oteseconazole, pirtobrutinib, regorafenib, resmetirom, ritonavir, rolapitant, roxadustat, tafamidis, teriflunomide, tolvaptan, turmeric, vadadustat, and zongertinib.(1,3-5) P-glycoprotein inhibitors linked to this monograph include: asunaprevir, belumosudil, capmatinib, carvedilol, cyclosporine, danicopan, daraxonrasib, daridorexant, diltiazem, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, imlunestrant, isavuconazonium, ivacaftor, ledipasvir, neratinib, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, tezacaftor, ticagrelor, valbenazine, verapamil, vimseltinib, and voclosporin.(3,4)

Selected Kinase Inhibitors/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: The solubility of bosutinib,(1) dacomitinib,(2) dasatinib,(3) erlotinib,(4) gefitinib,(5) neratinib,(6) nilotinib,(7) and pazopanib(8) is pH dependent. Changes in gastric pH from vonoprazan(9) may decrease the absorption of bosutinib,(1) dacomitinib,(2) dasatinib,(3) erlotinib,(4) gefitinib,(5) neratinib,(6) nilotinib,(7) and pazopanib.(8)

CLINICAL EFFECTS: Use of vonoprazan may result in decreased levels and effectiveness of bosutinib,(1) dacomitinib,(2) dasatinib,(3) erlotinib,(4) gefitinib,(5) neratinib,(6) nilotinib,(7) and pazopanib.(8)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid the use of vonoprazan(9) in patients receiving treatment with bosutinib,(1) dacomitinib,(2) dasatinib,(3) erlotinib,(4) gefitinib,(5) neratinib,(6) nilotinib,(7) and pazopanib.(8) Consider the use of short-acting antacids in these patients.(1-8) If antacids are used, separate the administration times by several hours(1-8) but at least 2 hours for bosutinib,(1) dasatinib,(3) and nilotinib,(7) 6 hours for gefitinib,(5) and 3 hours for neratinib.(6) If H2 antagonist therapy is required with dacomitinib, dacomitinib must be given once daily 10 hours after the H2 blocker and 6 hours before the next dose of the H2 blocker.(2) If H2 antagonist therapy is required with gefitinib, administer gefitinib 6 hours before or after H2-antagonists or antacids.(5) If H2 antagonist therapy is required with erlotinib, neratinib, or nilotinib, the kinase inhibitor must be given 10 hours after the H2 blocker and at least 2 hours before the next dose of the H2 blocker.(4,6,7) The manufacturer of Phyrago states that it can be administered with gastric acid reducing agents. Administration times should be separated with antacids.(14)

DISCUSSION: Vonoprazan decreases gastric acidity by suppressing gastric acid secretion and is characterized as a type of gastric proton-pump inhibitor.(9) In a pharmacodynamic study, a single 20 mg dose of vonoprazan, elevated the intragastric pH compared to placebo and was sustained for over 24-hours after dosing. The inhibitory effect of vonoprazan on acid secretion increased with repeated daily dosing and antisecretory effect reached steady state by Day 4 with a mean 24-hour intragastric pH of 6.0 following 20 mg once daily dose.(9) In a study, concurrent rabeprazole decreased the Cmax and AUC of dacomitinib by 51% and 39%, respectively.(2) In a study in 24 healthy subjects, administration of a single dose of dasatinib (50 mg) 10 hours after famotidine decreased dasatinib area-under-curve (AUC) and maximum concentration (Cmax) by 61% and 63%, respectively.(3) In a study in 14 healthy subjects, administration of a single dose of dasatinib (100 mg) 22 hours after omeprazole (40 mg at steady state) decreased dasatinib AUC and Cmax by 43% and 42%, respectively.(3) In a study in 24 healthy subjects, simultaneous administration of dasatinib (50 mg) with aluminum hydroxide/magnesium hydroxide (30 ml) decreased dasatinib AUC and Cmax by 55% and 58%, respectively. In the same subjects, administration of the antacid 2 hours before dasatinib decreased dasatinib Cmax by 26%, but had no effect on dasatinib AUC.(3) In a study, concurrent omeprazole decreased the AUC and Cmax of erlotinib by 46% and 61%, respectively.(4) In a study, administration of erlotinib two hours after a dose of ranitidine (300 mg), erlotinib AUC and Cmax decreased by 33% and 54%, respectively. Administration of erlotinib 10 hours after and two hours before ranitidine (150 mg twice daily), erlotinib AUC and Cmax decreased by 15% and 17%, respectively.(4) In a case report, a patient that was given erlotinib (150 mg daily,) with algeldrate/magnesium hydroxide (800/400 mg four times daily 4 hours before or 2 hours after erlotinib) did not see a significant reduction in serum trough concentrations of erlotinib. When the patient was switched to intravenous pantoprazole via continuous infusion (8 mg per hour), serum erlotinib levels decreased significantly below minimal trough concentrations for effective tyrosine kinase inhibition. When the patient was switched to oral pantoprazole (40 mg twice daily), serum trough levels of erlotinib returned to therapeutic levels.(10) In a study in healthy subjects, high dose ranitidine with sodium carbonate was administered to maintain gastric pH above 5.0 and gefitinib AUC decreased 47%.(5) In a study in 15 healthy subjects, lansoprazole (30 mg at steady state) decreased the Cmax and AUC of a single dose of neratinib (240 mg) by 71% and 65%, respectively.(6) In a study in 22 healthy subjects, pretreatment with esomeprazole (40 mg daily), decreased the Cmax and AUC of a single dose of nilotinib (400 mg) by 27% and 34%, respectively.(7,11) Increasing the dosage of nilotinib or separating the administration time of nilotinib and the proton pump inhibitor is not expected to eliminate the interaction.(7) There were no significant changes in nilotinib pharmacokinetics when famotidine was administered 10 hours before or 2 hours after nilotinib.(7) There were no significant changes in nilotinib pharmacokinetics when an antacid (aluminum hydroxide/magnesium hydroxide/simethicone) was administered 2 hours before or after nilotinib.(7) In a study in 13 patients, esomeprazole (40 mg daily for 5 days) decreased the Cmax and AUC of pazopanib (400 mg daily) by 42% and 40%, respectively, when compared to the administration of pazopanib alone.(12) In an open-label, crossover study in 17 evaluable patients, omeprazole (40 mg daily) had no significant effects on the pharmacokinetics, pharmacodynamics, or safety of bortezomib (1.3 mg/m2).(13) Phyrago is not sensitive to increased gastric pH due to its polymer formulation. No clinically significant pharmacokinetic changes were seen with concurrent administration of Phyrago with omeprazole (proton pump inhibitor) or famotidine (H2 receptor antagonist).(14)

Selected P-Glycoprotein (P-Gp) Inhibitors/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: Ensartinib is a P-glycoprotein (P-gp) substrate. P-gp inhibitors may increase the levels of ensartinib.(1)

CLINICAL EFFECTS: The concurrent administration of a P-glycoprotein (P-gp) inhibitor may result in elevated levels of and toxicity from ensartinib.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of ensartinib states that concurrent use of P-glycoprotein (P-gp) inhibitors should be avoided.(1) The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(4)

DISCUSSION: Ensartinib is a substrate of P-gp. Inhibitors of P-gp may increase toxicity of ensartinib.(1) Inhibitors of P-gp linked to this monograph include: abrocitinib, amiodarone, Asian ginseng (Panax ginseng), asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daraxonrasib, daridorexant, diosmin, eliglustat, flibanserin, fostamatinib, ginkgo biloba, glecaprevir and pibrentasvir, hydroquinidine, ivacaftor, lapatinib, mavorixafor, milk thistle (Silybum marianum), neratinib, osimertinib, propafenone, quercetin, quinidine, ranolazine, rolapitant, silibinin, silymarin, sotagliflozin, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, venetoclax, vepdegestrant, vilazodone, vimseltinib, and voclosporin.(2,3)

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

Neratinib/Strong Cyp3a4 Inhib;Moderate 3A4 & P-Gp Dual Inhib

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

MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of neratinib.(1)

CLINICAL EFFECTS: Concurrent use of strong CYP3A4 inhibitors or moderate CYP3A4 and P-glycoprotein (P-gp) dual inhibitors may result in increased systemic exposure to and effects from neratinib.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid the concurrent use of neratinib with strong CYP3A4 inhibitors or moderate CYP3A4 and P-gp dual inhibitors.(1) The Australian and Canadian manufacturer of nirmatrelvir/ritonavir state that concurrent use with neratinib is contraindicated due to the potential for hepatotoxicity and other serious reactions.(2,3) Canadian labeling contraindicates concurrent use of atazanavir/ritonavir and lopinavir/ritonavir with neratinib.(4,5) If concurrent use is warranted, monitor patients closely for increased incidence and severity of diarrhea, abdominal pain, nausea, vomiting, and dehydration.

DISCUSSION: Ketoconazole (400 mg daily for 5 days), a strong CYP3A4 inhibitor, increased maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of neratinib by 221% and 381%, respectively.(1) Pharmacokinetic models predicted that verapamil, a moderate CYP3A4 and P-gp dual inhibitor, would increase the Cmax and AUC of neratinib by 203% and 299%, respectively. Fluconazole, a moderate CYP3A4 inhibitor, is not expected to have a significant interaction with neratinib.(1) Strong CYP3A4 inhibitors include: adagrasib, boceprevir, clarithromycin, cobicistat, diltiazem, ensitrelvir, grapefruit juice, idelalisib, indinavir, itraconazole, ketoconazole, lonafarnib, mibefradil, mifepristone, nefazodone, nelfinavir, nirmatrelvir, posaconazole, ribociclib, telaprevir, telithromycin, troleandomycin, tucatinib, and voriconazole.(1,6) Moderate CYP3A4 and P-gp dual inhibitors include: atazanavir, conivaptan, diltiazem, dronedarone, erythromycin, isavuconazole, istradefylline, josamycin, nilotinib, and verapamil.(1,6)

P-Glycoprotein (P-Gp) Inhibitors/Bilastine

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

MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibition may increase the absorption of bilastine.(1,2)

CLINICAL EFFECTS: Concurrent use of P-gp inhibitors may result in elevated levels and toxicities from bilastine, including headache and somnolence.(1,2)

PREDISPOSING FACTORS: The interaction magnitude may be greater in patients with moderate to severe renal impairment.

PATIENT MANAGEMENT: The Canadian manufacturer of bilastine states that concomitant use of P-gp inhibitors with bilastine is not recommended. Coadministration should be avoided in patients with moderate or severe renal impairment.(1) The UK manufacturer of bilastine states that coadministration of bilastine and P-gp inhibitors should be avoided in patients with moderate to severe renal impairment.(2) The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(5)

DISCUSSION: In a study, ketoconazole and erythromycin both increased bilastine area-under-curve (AUC) and maximum concentration (Cmax) by 2-fold and 2- to 3-fold, respectively.(1) The UK manufacturer of bilastine states that these changes do not appear to affect the safety of bilastine.(2) P-gp inhibitors linked to this monograph include: amiodarone, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, daclatasvir, danicopan, daraxonrasib, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo, ginseng, glecaprevir/pibrentasvir, hydroquinidine, imlunestrant, istradefylline, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, paroxetine, pirtobrutinib, posaconazole, propafenone, quercetin, quinidine, quinine, ranolazine, sarecycline, schisandra, selpercatinib, simeprevir, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, tepotinib, valbenazine, vemurafenib, vepdegestrant, verapamil, vimseltinib, and voclosporin.(4,5)

P-Glycoprotein (P-Gp) Inhibitors/Colchicine (For Gout & Fmf)

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

MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may affect the transport of colchicine, a P-gp substrate.(1,2)

CLINICAL EFFECTS: Concurrent use of a P-gp inhibitor may result in elevated levels of and toxicity from colchicine. Symptoms of colchicine toxicity include abdominal pain; nausea or vomiting; severe diarrhea; muscle weakness or pain; numbness or tingling in the fingers or toes; myelosuppression; feeling weak or tired; increased infections; and pale or gray color of the lips, tongue, or palms of hands.(1,2)

PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with renal and/or hepatic impairment(1,2) and in patients who receive concurrent therapy.

PATIENT MANAGEMENT: The concurrent use of colchicine with P-gp inhibitors is contraindicated in patients with renal or hepatic impairment.(1-3) Avoid concurrent use in other patients, if possible.(3) In patients without renal or hepatic impairment who are currently taking or have taken a P-gp inhibitor in the previous 14 days, the dosage of colchicine should be reduced. For gout flares, the recommended dosage is 0.6 mg (1 tablet) for one dose. This dose should be repeated no earlier than in 3 days.(1,2) For gout prophylaxis, if the original dosage was 0.6 mg twice daily, use 0.3 mg daily. If the original dosage was 0.6 mg daily, use 0.3 mg every other day.(3-12) For Familial Mediterranean fever (FMF), the recommended maximum daily dose is 0.6 mg (may be given as 0.3 mg twice a day).(1,2) Patients should be instructed to immediately report any signs of colchicine toxicity, such as abdominal pain, nausea/significant diarrhea, vomiting; muscle weakness/pain; numbness/tingling in fingers/toes; unusual bleeding or bruising, infections, weakness/tiredness, or pale/gray color of the lips/tongue/palms of hands. The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(13)

DISCUSSION: There are several reports of colchicine toxicity(4-6) and death(7,8) following the addition of clarithromycin to therapy. In a retrospective review of 116 patients who received clarithromycin and colchicine during the same hospitalization, 10.2% (9/88) of patients who received simultaneous therapy died, compared to 3.6% (1/28) of patients who received sequential therapy.(9) An FDA review of 117 colchicine-related deaths that were not attributable to overdose found that 60 deaths (51%) involved concurrent use of clarithromycin.(2) There is one case report of colchicine toxicity with concurrent erythromycin.(10) In a study in 20 subjects, pretreatment with diltiazem (240 mg daily for 7 days) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of colchicine (0.6 mg) by 44.2% (range -46.6% to 318.3%) and by 93.4% (range -30.2% to 338.6%), respectively.(1) In a study in 24 subjects, pretreatment with verapamil (240 mg twice daily for 7 days) increased the Cmax and AUC of a single dose of colchicine (0.6 mg) by 40.1% (range -47.1% to 149.5%) and by 103.3% (range -9.8% to 217.2%), respectively.(1) Colchicine toxicity has been reported with concurrent use of CYP3A4 and P-gp inhibitors such as clarithromycin, cyclosporine, diltiazem, erythromycin, and verapamil.(1,2) P-gp inhibitors include abrocitinib, amiodarone, asciminib, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, danicopan, daraxonrasib, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, imlunestrant, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, valbenazine, velpatasvir, vemurafenib, venetoclax, vepdegestrant, verapamil, vimseltinib, and voclosporin.(1,11,12)

P-Glycoprotein (P-Gp) Inhibitors/Pralsetinib

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

MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may inhibit cellular efflux of pralsetinib.(1)

CLINICAL EFFECTS: Concurrent administration of a P-gp inhibitor may result in elevated levels of and toxicity from pralsetinib, including hemorrhagic events, pneumonitis, hepatotoxicity, hypertension, and QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias like torsades de pointes (TdP).(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)

PATIENT MANAGEMENT: Coadministration of pralsetinib with a P-gp inhibitor should be avoided.(1) If coadministration with a P-gp inhibitor cannot be avoided, use with caution and reduce the dose of pralsetinib as follows: -If the current dose is 400 mg once daily, decrease the dose to 300 mg daily. -If the current dose is 300 mg once daily, decrease the dose to 200 mg daily. -If the current dose is 200 mg once daily, decrease the dose to 100 mg daily. After the inhibitor is discontinued for three to five half-lives, resume the dose of pralsetinib at the dose taken prior to initiation of the inhibitor.(1) The manufacturer of venetoclax states that if concurrent use with a P-gp substrate cannot be avoided, take pralsetinib at least 6 hours before venetoclax.(5) The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(8) 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 the QTc interval exceeds 500 ms, interrupt pralsetinib therapy until QTc is <470 ms. Resume pralsetinib at the same dose if risk factors that cause QT prolongation an are identified and corrected. If risk factors that cause QT prolongation are not identified, resume pralsetinib at a reduced dose. Permanently discontinue pralsetinib if the patient develops life-threatening arrhythmia.(3)

DISCUSSION: Coadministration of a single dose of cyclosporine 600 mg (a P-gp inhibitor) with a single pralsetinib 200 mg dose increased pralsetinib concentration maximum (Cmax) by 48% and area-under-curve (AUC) by 81%.(1) P-glycoprotein inhibitors linked to this monograph include: asunaprevir, belumosudil, carvedilol, cyclosporine, danicopan, daraxonrasib, daridorexant, deutivacaftor, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, ivacaftor, ledipasvir, neratinib, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, valbenazine, venetoclax, vimseltinib, and voclosporin.(6,7)

P-Glycoprotein (P-Gp) Inhibitors/Relugolix

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

MECHANISM OF ACTION: Relugolix is a substrate of the intestinal P-glycoprotein (P-gp) efflux transporter. Inhibitors of P-gp may increase the absorption of relugolix.(1)

CLINICAL EFFECTS: The concurrent administration of relugolix with an inhibitor of P-glycoprotein may result in elevated levels of relugolix and adverse effects, including hot flashes, skin flushing, musculoskeletal pain, hyperglycemia, acute renal injury, transaminitis, arrhythmias, and hemorrhage.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of relugolix states that the coadministration of relugolix with P-gp inhibitors should be avoided. If the P-gp inhibitor is to be used short-term, relugolix may be held for up to 2 weeks. If treatment with relugolix is interrupted for longer than 7 days, resume relugolix with a loading dose of 360 mg on the first day, followed by 120 mg once daily.(1) If coadministration with a P-gp inhibitor cannot be avoided, relugolix should be taken at least 6 hours before the P-gp inhibitor. Monitor the patient more frequently for adverse events.(1) For patients on daraxonrasib, the manufacturer of daraxonrasib states that it should be taken at least 4 hours apart from P-gp substrates.(2)

DISCUSSION: Coadministration of relugolix with erythromycin (a P-gp and moderate CYP3A4 inhibitor) increased the area-under-curve (AUC) and maximum concentration (Cmax) of relugolix by 6.2-fold. Voriconazole (a strong CYP3A4 inhibitor) did not have a clinically significant effect on the pharmacokinetics of relugolix.(1) P-gp inhibitors linked to this monograph include: amiodarone, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, curcumin, cyclosporine, daclatasvir, danicopan, daraxonrasib, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo, ginseng, glecaprevir/pibrentasvir, indinavir, itraconazole, ivacaftor, josamycin, ketoconazole, lapatinib, lonafarnib, mavorixafor, mibefradil, mifepristone, neratinib, osimertinib, paroxetine, pirtobrutinib, posaconazole, propafenone, quinidine, quinine, ranolazine, ritonavir, sarecycline, schisandra, selpercatinib, simeprevir, sotorasib, telaprevir, telithromycin, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, venetoclax, vepdegestrant, verapamil, vimseltinib, and voclosporin.(3,4)

P-Glycoprotein (P-Gp) Inhibitors/Vincristine

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

MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may inhibit cellular efflux of vincristine.(1)

CLINICAL EFFECTS: Concurrent administration of a P-gp inhibitor may result in elevated levels of and toxicity from vincristine including myelosuppression, neurologic toxicity, tumor lysis syndrome, hepatotoxicity, constipation, or bowel obstruction.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid the use of P-gp inhibitors in patients undergoing therapy with vincristine.(1) Consider alternatives with no or minimal P-gp inhibition. The manufacturer of vincristine states that concomitant use of P-gp inhibitors should be avoided.(1) The manufacturer of lopinavir/ritonavir states that patients who develop significant hematological or gastrointestinal toxicity on concomitant vincristine should temporarily hold lopinavir/ritonavir, or use alternative medications that do not inhibit CYP3A4 or P-gp.(2) The manufacturer of daraxonrasib states that it should be taken at least 4 hours apart from P-gp substrates.(3)

DISCUSSION: Vincristine is a substrate of P-gp. Inhibitors of P-gp may increase toxicity of vincristine.(1) There are several case reports of neurotoxicity with concurrent administration of vincristine and itraconazole.(4-6) There is a case report of neurotoxicity with concurrent administration of lopinavir-ritonavir with vincristine.(7) In a prospective study in 22 children receiving various chemotherapy with prophylactic itraconazole oral solution (0.5 ml/kg per day), two children receiving vincristine developed non-alcoholic steatohepatitis (NASH) and one child developed syndrome of inappropriate anti-diuretic hormone secretion (SIADH).(8) Inhibitors of P-gp linked to this monograph include: abrocitinib, amiodarone, Asian ginseng (Panax ginseng), asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daraxonrasib, daridorexant, deutivacaftor, diltiazem, diosmin, dronedarone, elagolix, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo biloba, glecaprevir and pibrentasvir, imlunestrant, isavuconazonium, ivacaftor, lapatinib, mavorixafor, milk thistle (Silybum marianum), neratinib, osimertinib, pirtobrutinib, propafenone, quercetin, quinidine, ranolazine, rolapitant, Schisandra chinensis, selpercatinib, sofosbuvir, sotorasib, tepotinib, valbenazine, velpatasvir, vemurafenib, venetoclax, vepdegestrant, verapamil, vilazodone, vimseltinib, and voclosporin.(9-10)

Selected Kinase Inhibitors/Proton Pump Inhibitors

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

MECHANISM OF ACTION: The solubility of bosutinib,(1) dacomitinib,(2) dasatinib,(3) erlotinib,(4) gefitinib,(5) neratinib,(6) nilotinib,(7) pazopanib(8), and pexidartinib (9) is pH dependent. Changes in gastric pH from proton pump inhibitors may decrease the absorption of bosutinib,(1) dacomitinib,(2) dasatinib,(3) erlotinib,(4) gefitinib,(5) neratinib,(6) nilotinib,(7) pazopanib,(8) and pexidartinib.(9)

CLINICAL EFFECTS: Use of proton pump inhibitors may result in decreased levels and effectiveness of bosutinib,(1) dacomitinib,(2) dasatinib,(3) erlotinib,(4) gefitinib,(5) neratinib,(6) nilotinib,(7) pazopanib,(8) and pexidartinib.(9)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid the use of proton pump inhibitors (PPIs) in patients receiving treatment with bosutinib,(1) dacomitinib,(2) dasatinib,(3) erlotinib,(4) gefitinib,(5) neratinib,(6) nilotinib,(7) pazopanib,(8) and pexidartinib.(9) Consider the use of short-acting antacids in these patients.(1-9) If antacids are used, separate the administration times by several hours(1-9) but at least 2 hours for bosutinib,(1) dasatinib,(3) nilotinib,(7) and pexidartinib(9), 6 hours for gefitinib,(5) and 3 hours for neratinib.(6) If PPIs are required with gefitinib, administer gefitinib 12 hours after the last dose or 12 hours before the next dose of the PPI. Administer gefitinib 6 hours before or after H2-antagonists or antacids.(5) If H2 antagonist therapy is used with bosutinib, separate administration by at least 2 hours.(1) If H2 antagonist therapy is required with dacomitinib, dacomitinib must be given once daily 10 hours after the H2 blocker and 6 hours before the next dose of the H2 blocker.(2) If H2 antagonist therapy is required with erlotinib, neratinib, nilotinib, or pexidartinib, the kinase inhibitor must be given 10 hours after the H2 blocker and at least 2 hours before the next dose of the H2 blocker.(4,6,7,9) If H2 antagonist therapy is required with gefitinib, gefitinib should be given at least 6 hours before or after the H2 antagonist.(5) The manufacturer of Phyrago states that it can be administered with gastric acid reducing agents. Administration times should be separated with antacids.

DISCUSSION: In a study, concurrent rabeprazole decreased the Cmax and AUC of dacomitinib by 51% and 39%, respectively.(2) In a study in 24 healthy subjects, administration of a single dose of dasatinib (50 mg) 10 hours after famotidine decreased dasatinib area-under-curve (AUC) and maximum concentration (Cmax) by 61% and 63%, respectively.(3) In a study in 14 healthy subjects, administration of a single dose of dasatinib (100 mg) 22 hours after omeprazole (40 mg at steady state) decreased dasatinib AUC and Cmax by 43% and 42%, respectively.(3) In a study in 24 healthy subjects, simultaneous administration of dasatinib (50 mg) with aluminum hydroxide/magnesium hydroxide (30 ml) decreased dasatinib AUC and Cmax by 55% and 58%, respectively. In the same subjects, administration of the antacid 2 hours before dasatinib decreased dasatinib Cmax by 26%, but had no effect on dasatinib AUC.(3) In a study, concurrent omeprazole decreased the AUC and Cmax of erlotinib by 46% and 61%, respectively.(4) In a study, administration of erlotinib two hours after a dose of ranitidine (300 mg), erlotinib AUC and Cmax decreased by 33% and 54%, respectively. Administration of erlotinib 10 hours after and two hours before ranitidine (150 mg twice daily), erlotinib AUC and Cmax decreased by 15% and 17%, respectively.(4) In a case report, a patient that was given erlotinib (150 mg daily,) with algeldrate/magnesium hydroxide (800/400 mg four times daily 4 hours before or 2 hours after erlotinib) did not see a significant reduction in serum trough concentrations of erlotinib. When the patient was switched to intravenous pantoprazole via continuous infusion (8 mg per hour), serum erlotinib levels decreased significantly below minimal trough concentrations for effective tyrosine kinase inhibition. When the patient was switched to oral pantoprazole (40 mg twice daily), serum trough levels of erlotinib returned to therapeutic levels.(9) In a study in healthy subjects, high dose ranitidine with sodium carbonate was administered to maintain gastric pH above 5.0 and gefitinib AUC decreased 47%.(5) In a study in 15 healthy subjects, lansoprazole (30 mg at steady state) decreased the Cmax and AUC of a single dose of neratinib (240 mg) by 71% and 65%, respectively.(6) In a study in 22 healthy subjects, pretreatment with esomeprazole (40 mg daily), decreased the Cmax and AUC of a single dose of nilotinib (400 mg) by 27% and 34%, respectively.(7,10) Increasing the dosage of nilotinib or separating the administration time of nilotinib and the proton pump inhibitor is not expected to eliminate the interaction.(7) There were no significant changes in nilotinib pharmacokinetics when famotidine was administered 10 hours before or 2 hours after nilotinib.(7) There were no significant changes in nilotinib pharmacokinetics when an antacid (aluminum hydroxide/magnesium hydroxide/simethicone) was administered 2 hours before or after nilotinib.(7) In a study in 13 patients, esomeprazole (40 mg daily for 5 days) decreased the Cmax and AUC of pazopanib (400 mg daily) by 42% and 40%, respectively, when compared to the administration of pazopanib alone.(11) In an open-label, crossover study in 17 evaluable patients, omeprazole (40 mg daily) had no significant effects on the pharmacokinetics, pharmacodynamics, or safety of bortezomib (1.3 mg/m2).(12) Coadministration of esomeprazole decreased pexidartinib Cmax and AUC by 55% and 50%. (13) Phyrago is not sensitive to increased gastric pH due to its polymer formulation. No clinically significant dasatinib pharmacokinetic changes were seen with concurrent administration of Phyrago with omeprazole (proton pump inhibitor) or famotidine (H2 receptor antagonist).(14)

Selected P-Glycoprotein (P-Gp) Inhibitors/Dabigatran

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

MECHANISM OF ACTION: Dabigatran etexilate is a substrate for the P-glycoprotein (P-gp) system. Inhibition of intestinal P-gp leads to increased absorption of dabigatran.(1-3)

CLINICAL EFFECTS: The concurrent use dabigatran with P-gp inhibitors may lead to elevated plasma levels of dabigatran, increasing the risk for bleeding.

PREDISPOSING FACTORS: Factors associated with an increased risk for bleeding include renal impairment, concomitant use of P-gp inhibitors, patient age >74 years, coexisting conditions (e.g. recent trauma) or use of drugs (e.g. NSAIDs) associated with bleeding risk, and patient weight < 50 kg.(1-4)

PATIENT MANAGEMENT: Assess renal function and evaluate patient for other pre-existing risk factors for bleeding prior to initiating concurrent therapy. The US manufacturer of dabigatran states that the concurrent use of dabigatran and P-gp inhibitors should be avoided in atrial fibrillation patients with severe renal impairment (CrCl less than 30 ml/min) and in patients with moderate renal impairment (CrCl less than 50 ml/min) being treated for or undergoing prophylaxis for deep vein thrombosis (DVT) or pulmonary embolism (PE). The interaction with P-gp inhibitors can be minimized by taking dabigatran several hours apart from the P-gp inhibitor dose.(1) The concomitant use of dabigatran with P-gp inhibitors has not been studied in pediatric patients but may increase exposure to dabigatran.(1) While the US manufacturer of dabigatran states that no dosage adjustment is necessary in other patients,(1) the Canadian manufacturer of dabigatran states that concomitant use of strong P-gp inhibitors (e.g., glecaprevir-pibrentasvir) is contraindicated. When dabigatran is used for the prevention of venous thromboembolism (VTE) after total hip or knee replacement concurrently with amiodarone, quinidine, or verapamil, the dose of dabigatran should be reduced from 110 mg twice daily to 150 mg once daily. For patients with CrCl less than 50 ml/min on verapamil, a further dabigatran dose reduction to 75 mg once daily should be considered. Verapamil should be given at least 2 hours after dabigatran to minimize the interaction.(2) The UK manufacturer of dabigatran also states the use of dabigatran with strong P-gp inhibitors (e.g., cyclosporine, glecaprevir-pibrentasvir or itraconazole) is contraindicated. Concurrent use of ritonavir is not recommended. When dabigatran is used in atrial fibrillation patients and for treatment of DVT and PE concurrently with verapamil, the UK manufacturer recommends reducing the dose of dabigatran from 150 mg twice daily to 110 mg twice daily, taken simultaneously with verapamil. When used for VTE prophylaxis after orthopedic surgery concurrently with amiodarone, quinidine, or verapamil, the dabigatran loading dose should be reduced from 110 mg to 75 mg, and the maintenance dose should be reduced from 220 mg daily to 150 mg daily, taken simultaneously with the P-gp inhibitor. For patients with CLcr 30-50 mL/min on concurrent verapamil, consider further lowering the dabigatran dose to 75 mg daily.(3) If concurrent therapy is warranted, monitor patients for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Consider regular monitoring of hemoglobin, platelet levels, and/or activated partial thromboplastin time (aPTT) or ecarin clotting time (ECT). When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(10)

DISCUSSION: When dabigatran was co-administered with amiodarone, the extent and rate of absorption of amiodarone and its active metabolite DEA were essentially unchanged. The dabigatran area-under-curve (AUC) and maximum concentration (Cmax) were increased by about 60% and 50%, respectively;(1,2) however, dabigatran clearance was increased by 65%.(1) Pretreatment with quinidine (200 mg every 2 hours to a total dose of 1000 mg) increased the AUC and Cmax of dabigatran by 53% and 56%, respectively.(1,2) Chronic administration of immediate release verapamil one hour prior to dabigatran dose increased dabigatran AUC by 154%.(4) Administration of dabigatran two hours before verapamil results in a negligible increase in dabigatran AUC.(1) Administration of sofosbuvir-velpatasvir-voxilaprevir (400/100/200 mg daily) increased the Cmax and AUC of a single dose of dabigatran (75 mg) by 2.87-fold and 2.61-fold, respectively.(5) Simultaneous administration of glecaprevir-pibrentasvir (300/120 mg daily) with a single dose of dabigatran (150 mg) increased the Cmax and AUC by 2.05-fold and 2.38-fold, respectively.(6) A retrospective comparative effectiveness cohort study including data from 9,886 individuals evaluated adverse bleeding rates with standard doses of oral anticoagulants with concurrent verapamil or diltiazem in patients with nonvalvular atrial fibrillation and normal kidney function. The study compared rates of bleeding following co-administration of either dabigatran, rivaroxaban, or apixaban with verapamil or diltiazem, compared to co-administration with amlodipine or metoprolol. Results of the study found that concomitant dabigatran use with verapamil or diltiazem was associated with increased overall bleeding (hazard ratio (HR) 1.52; 95% confidence interval (CI), 1.05-2.20, p<0.05) and increased overall GI bleeding (HR 2.16; 95% CI, 1.30-3.60, p<0.05) when compared to amlodipine. When compared to metoprolol, concomitant dabigatran use with verapamil or diltiazem was also associated with increased overall bleeding (HR, 1.43; 95% CI, 1.02-2.00, p<0.05) and increased overall GI bleeding (HR, 2.32; 95% CI, 1.42-3.79, p<0.05). No association was found between increased bleeding of any kind and concurrent use of rivaroxaban or apixaban with verapamil or diltiazem.(7) A summary of pharmacokinetic interactions with dabigatran and amiodarone or verapamil concluded that concurrent use is considered safe if CrCl is greater than 50 ml/min but should be avoided if CrCl is less than 50 ml/min in VTE and less than 30 ml/min for NVAF. Concurrent use with diltiazem was considered safe.(9) P-gp inhibitors include amiodarone, asunaprevir, aumolertinib, belumosudil, capmatinib, carvedilol, cimetidine, conivaptan, cyclosporine, daclatasvir, danicopan, daraxonrasib, daridorexant, diosmin, erythromycin, flibanserin, fostamatinib, ginseng, glecaprevir, imlunestrant, indinavir, itraconazole, ivacaftor, josamycin, lapatinib, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir, posaconazole, propafenone, quinidine, ranolazine, ritonavir, selpercatinib, sotorasib, telaprevir, telithromycin, tepotinib, tezacaftor, tucatinib, valbenazine, velpatasvir, vemurafenib, vepdegestrant, verapamil, vimseltinib, voclosporin, and voxilaprevir.(1-9)

Selected P-Glycoprotein (P-Gp) Inhibitors/Venetoclax

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

MECHANISM OF ACTION: Venetoclax is a substrate for the P-glycoprotein (P-gp) system. P-gp inhibitors may lead to increased levels of venetoclax.(1)

CLINICAL EFFECTS: Concurrent use of P-gp inhibitors may result in elevated levels of venetoclax, increasing the risk for tumor lysis syndrome and other toxicities.(1)

PREDISPOSING FACTORS: Risk factors for tumor lysis syndrome include (1): - the ramp-up phase of venetoclax therapy when tumor burden is highest - initial magnitude of tumor burden - renal impairment The risk of venetoclax toxicities may be increased in patients with severe hepatic impairment.(1)

PATIENT MANAGEMENT: Avoid P-gp inhibitors and consider alternative treatments when possible. If a P-gp inhibitor must be used, reduce venetoclax dose by at least 50%. Monitor more closely for signs of toxicity such as tumor lysis syndrome, hematologic and non-hematologic toxicities.(1) If the P-gp inhibitor is discontinued, the manufacturer of venetoclax recommends resuming the prior (i.e. pre-inhibitor) dose of venetoclax 2 to 3 days after discontinuation of the P-gp inhibitor.(1) For patients on daraxonrasib, the manufacturer of daraxonrasib states that it should be taken at least 4 hours apart from P-gp substrates.(2)

DISCUSSION: In 11 healthy subjects, a single dose of rifampin (a P-gp inhibitor) increased venetoclax maximum concentration (Cmax) and area-under-curve (AUC) by 106% and 78%, respectively.(1) In 11 previously treated NHL subjects, ketoconazole (a strong CYP3A4 inhibitor which also inhibits P-gp and BCRP) 400 mg daily for 7 days increased the Cmax and AUC of venetoclax 2.3-fold and 6.4-fold respectively.(1) In 12 healthy subjects, coadministration of azithromycin (500 mg Day 1, 250 mg for Days 2-5) decreased venetoclax Cmax and AUC by 25% and 35%. No dosage adjustment is needed when venetoclax is coadministered with azithromycin.(1) P-gp inhibitors include: amiodarone, asunaprevir, aumolertinib, belumosudil, capmatinib, carvedilol, cyclosporine, danicopan, daraxonrasib, daridorexant, diosmin, flibanserin, fostamatinib, ginseng, imlunestrant, ivacaftor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tezacaftor, tepotinib, valbenazine, vemurafenib, vepdegestrant, vimseltinib, and voclosporin.(3)

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

Bosutinib; Neratinib/Selected H2 Antagonists

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

MECHANISM OF ACTION: The solubility of bosutinib(1) and neratinib(2) is pH dependent. Changes in gastric pH from H2 antagonists may decrease the absorption of bosutinib and neratinib.

CLINICAL EFFECTS: Use of H2 antagonists may result in decreased levels and effectiveness of bosutinib(1) and neratinib.(2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Consider the use of short-acting antacids in patients taking bosutinib(1) and neratinib.(2) If antacids are used, separate the administration times by at least 2 hours for bosutinib(1) and 3 hours for neratinib.(2) If H2 antagonist therapy is required with bosutinib, separate administration of the H2 blocker by at least 2 hours before or 2 hours after bosutinib.(1) If H2 antagonist therapy is required with neratinib, then neratinib must be given 10 hours after the H2 blocker and at least 2 hours before the next dose of the H2 blocker.(2) Avoid the use of proton pump inhibitors (PPIs) in patients receiving treatment with bosutinib(1) and neratinib.(2)

DISCUSSION: A single dose of bosutinib 400 mg was administered alone or following multiple doses of lansoprazole 60 mg without food. Lansoprazole decreased bosutinib maximum concentration (Cmax) and area-under-curve (AUC) by 46% and 26%, respectively.(1) In a study in 15 healthy subjects, lansoprazole 30 mg daily decreased the Cmax and AUC of a single dose of neratinib (240 mg) by 71% and 65%, respectively.(2)

P-Glycoprotein (P-Gp) Inhibitors/Afatinib

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

MECHANISM OF ACTION: Inhibitors of P-glycoprotein (P-gp) may increase the absorption of afatinib.(1)

CLINICAL EFFECTS: The concurrent administration of afatinib with an inhibitor of P-glycoprotein may result in elevated levels of afatinib and signs of toxicity. These signs may include but are not limited to worsening diarrhea, stomatitis, skin rash/exfoliation/bullae or paronychia.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of afatinib states the afatinib dose should be reduced by 10 mg if the addition of a P-glycoprotein inhibitor is not tolerated.(1) If afatinib dose was reduced due to addition of a P-gp inhibitor, resume the previous dose after the P-gp inhibitor is discontinued.(1) The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to afatinib.(2) The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(4)

DISCUSSION: A drug interaction study evaluated the effects of ritonavir 200 mg twice daily on afatinib exposure. Administration of ritonavir 1 hour before afatinib administration increased systemic exposure by 48%. Afatinib exposure was not changed when ritonavir was administered simultaneously with or 6 hours after afatinib dose.(1) P-glycoprotein inhibitors linked to this monograph are: amiodarone, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, cyclosporine, danicopan, daraxonrasib, daridorexant, deutivacaftor, diosmin, dronedarone, erythromycin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, imlunestrant, isavuconazonium, itraconazole, ivacaftor, josamycin, ketoconazole, lapatinib, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, posaconazole, propafenone, quinidine, ranolazine, ritonavir, saquinavir, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, telaprevir, tepotinib, tucatinib, valbenazine, vemurafenib, vepdegestrant, verapamil, vimseltinib and voclosporin.(1-3)

P-Glycoprotein (P-Gp) Inhibitors/Etoposide

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

MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibition may increase etoposide cellular concentration, decrease biliary or renal elimination, and increase systemic absorption of oral etoposide.(1-4)

CLINICAL EFFECTS: Increased cellular or systemic levels of etoposide may result in etoposide toxicity.

PREDISPOSING FACTORS: The interaction magnitude may be greater in patients receiving oral etoposide, or with impaired renal or hepatic function.

PATIENT MANAGEMENT: Anticipate and monitor for increased hematologic and gastrointestinal toxicities. Adjust or hold etoposide dose when needed. In patients receiving high-dose cyclosporine therapy, etoposide dosages should be reduced by 50%.(1) Monitor for signs of etoposide toxicity. Dosages may need further adjustment. The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to etoposide.(5) The manufacturer of daraxonrasib states that P-gp substrates should be taken 4 hours apart from daraxonrasib.(6)

DISCUSSION: In a study in 16 patients, the administration of etoposide plus cyclosporine increased etoposide area-under-curve (AUC) by 59% and half-life by 73%. Etoposide renal clearance was decreased by 38% and nonrenal clearance was decreased by 52%. White blood cell count nadir was significantly lower during concurrent therapy with cyclosporine and etoposide (1200 mm3) when compared to etoposide alone (2500 mm3). There was also a trend for higher dosages of cyclosporine to exert increased effects on etoposide, although this difference did not reach statistical significance.(1) P-gp inhibitors linked to this monograph include: asciminib, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, cimetidine, clarithromycin, cyclosporine, daraxonrasib, daridorexant, danicopan, deutivacaftor, diosmin, flibanserin, fostamatinib, glecaprevir/pibrentasvir, imlunestrant, itraconazole, ivacaftor, josamycin, ketoconazole, lonafarnib, mavorixafor, neratinib, osimertinib, pirtobrutinib, posaconazole, propafenone, quinidine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, tepotinib, tucatinib, valbenazine, vemurafenib, vepdegestrant, verapamil, vimseltinib, and voclosporin.

P-Glycoprotein (P-Gp) Inhibitors/Mavorixafor

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

MECHANISM OF ACTION: Mavorixafor is a substrate of the P-glycoprotein (P-gp) transporter. P-gp inhibitors may significantly increase the absorption of mavorixafor.(1)

CLINICAL EFFECTS: Concurrent administration of mavorixafor with an inhibitor of P-glycoprotein may result in elevated levels of and effects from mavorixafor, including potentially life-threatening cardiac arrhythmias, torsades de pointes, and sudden death.(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)

PATIENT MANAGEMENT: When used concomitantly with P-gp inhibitors, monitor more frequently for mavorixafor adverse effects and reduce the dose in 100 mg increments, if necessary, but not to a dose less than 200 mg.(1) The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to mavorixafor.(4) 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: In a study with healthy subjects, itraconazole 200 mg daily (a strong CYP3A4 and P-gp inhibitor) increased the exposure to single-dose mavorixafor 200 mg similar to that from single-dose mavorixafor 400 mg alone. This suggests that itraconazole increased mavorixafor exposure by about 2-fold.(1) A study in healthy volunteers found that ritonavir 100 mg twice daily (a strong CYP3A4 inhibitor and P-gp inhibitor) increased the area-under-curve (AUC) and maximum concentration (Cmax) of single-dose mavorixafor 200 mg by 60% and 39%, respectively.(1) P-glycoprotein inhibitors linked to this monograph include: abrocitinib, Asian ginseng, asunaprevir, capmatinib, carvedilol, cyclosporine, danicopan, daridorexant, deutivacaftor, diosmin, elagolix, flibanserin, fostamatinib, ginkgo biloba, glecaprevir/pibrentasvir, ivacaftor, milk thistle, neratinib, pirtobrutinib, quercetin, rolapitant, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, velpatasvir, vilazodone, vimseltinib, and voclosporin.(1,4-6)

P-Gp Inhibitors/Daraxonrasib (<= 150 Mg)

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

MECHANISM OF ACTION: Daraxonrasib is a substrate of P-gp. P-gp inhibitors may inhibit the metabolism of daraxonrasib.(1)

CLINICAL EFFECTS: Concurrent use of P-gp inhibitors may increase the levels and toxicities of daraxonrasib, including dermatologic toxicity, stomatitis, GI perforation, and interstitial lung disease/pneumonitis.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: For patients taking agents that are P-gp inhibitors, reduce the dose of daraxonrasib from 300 mg to 150 mg daily. After the P-gp inhibitor has been discontinued, resume the daraxonrasib dosage taken prior to initiating the inhibitor.(1)

DISCUSSION: In a pharmacokinetic model, quinidine 300 mg three times daily (a P-gp inhibitor) increased the area under curve (AUC) of daraxonrasib by 1.8-fold.(1) P-gp inhibitors include: abrocitinib, amiodarone, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, curcumin, danicopan, daridorexant, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, imlunestrant, ivacaftor, lapatinib, neratinib, osimertinib, pirtobrutinib, propafenone, ranolazine, selpercatinib, tepotinib, tezacaftor, turmeric, valbenazine, velpatasvir, vemurafenib, vepdegestrant, vimseltinib, and voclosporin.(2-3)

P-Gp Or Bcrp Inhibitors/Ubrogepant (<= 50 Mg)

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

MECHANISM OF ACTION: Inhibitors of P-glycoprotein (P-gp) or BCRP may increase the absorption of ubrogepant.(1)

CLINICAL EFFECTS: The concurrent administration of ubrogepant with an inhibitor of P-glycoprotein or BCRP may result in elevated levels of ubrogepant.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when coadministered with P-gp or BCRP inhibitors. 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.(1) For patients on concurrent therapy with vimseltinib and ubrogepant: The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to ubrogepant.(3) For patients on daraxonrasib, the manufacturer of daraxonrasib states that it should be taken at least 4 hours apart from P-gp substrates.(4)

DISCUSSION: Ubrogepant is a substrate of P-gp and BCRP transporters. 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. The US manufacturer of ubrogepant recommends dose adjustment if ubrogepant is coadministered with P-gp or BCRP inhibitors.(1) BCRP inhibitors linked to this monograph include: belumosudil, clopidogrel, curcumin, eltrombopag, febuxostat, fostemsavir, leniolisib, momelotinib, oteseconazole, regorafenib, resmetirom, ritonavir, rolapitant, roxadustat, tafamidis, oral tedizolid, turmeric, vadadustat, and zongertinib.(2,3,5,6) P-glycoprotein inhibitors linked to this monograph include: asunaprevir, belumosudil, capmatinib, carvedilol, danicopan, daraxonrasib, daridorexant, imlunestrant, neratinib, osimertinib, propafenone, quinidine, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, valbenazine, vimseltinib, and voclosporin.(2,3,5,6)

Select P-Gp Inhibitors/Edoxaban (<= 30 Mg)

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

MECHANISM OF ACTION: Edoxaban is a substrate for P-glycoprotein (P-gp). Inhibitors of P-gp may increase intestinal absorption and decrease renal tubular elimination of edoxaban.(1,2)

CLINICAL EFFECTS: Concurrent use with selected P-gp inhibitors may result in higher systemic concentrations of edoxaban which may increase the risk for bleeding.(1,2)

PREDISPOSING FACTORS: Bleeding risk may be increased in patients with creatinine clearance below 50 mL per minute(1-4). Use of multiple agents which increase edoxaban exposure or affect hemostasis would be expected to increase the risk for bleeding. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: Management recommendations between approving regulatory agencies (FDA or European Medicines Agency, EMA) are conflicting. EMA approved prescribing information specifically states that dosage adjustments are not required solely for concomitant use with amiodarone, quinidine, or verapamil regardless of indication.(3,4) Potential interactions with azithromycin, clarithromycin, or oral itraconazole are not described.(3) FDA approved prescribing recommendations for edoxaban are indication specific:(2) - For prevention of stroke or embolic events due to nonvalvular atrial fibrillation, no edoxaban dose adjustments are recommended during concomitant therapy with P-glycoprotein inhibitors. - For treatment of deep vein thrombosis (DVT) or pulmonary embolism (PE), the edoxaban dose should be reduced to 30 mg daily during concomitant use with azithromycin, clarithromycin, oral itraconazole, quinidine or verapamil. The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to edoxaban.(6) Monitor patients receiving anticoagulant therapy for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. anti Factor Xa inhibition) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. Discontinue edoxaban in patients with active bleeding. The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(9)

DISCUSSION: Edoxaban in vivo interaction studies have been performed for quinidine and verapamil. In vivo interaction studies have not been conducted for the remaining P-gp inhibitors linked to this monograph.(1,4) In an interaction study, the effect of repeat administration of quinidine (300 mg TID) on a single oral dose of edoxaban 60 mg was evaluated in healthy subjects. Both peak (Cmax) and total systemic exposure (AUC) to edoxaban and to the active M4 metabolite increased approximately 1.75-fold.(1) In an interaction study, the effect of repeat administration of verapamil (240 mg Verapamil SR Tablets (Calan SR) QD for 11 Days) on a single oral dose of edoxaban 60 mg on the morning of Day 10 was evaluated in healthy subjects. Total and peak systemic exposure to edoxaban increased 1.53-fold and 1.53-fold, respectively. Total and peak systemic exposure to the active M4 metabolite increased 1.31-fold and 1.28-fold, respectively.(1) Based upon the above results, patients in the DVT/PE trial had a 50% dose reduction (from 60 mg to 30 mg) during concomitant therapy with P-glycoprotein inhibitors. Approximately 0.5% of these patients required a dose reduction solely due to P-gp inhibitor use. This low rate of concurrent therapy was too small to allow for detailed statistical evaluation. Almost all of these patients were receiving quinidine or verapamil. In these patients, both trough edoxaban concentrations (Ctrough) used to evaluate bleeding risk, and total edoxaban exposure (AUC or area-under-curve) used to evaluate treatment efficacy, were lower than patients who did not require any edoxaban dose adjustment. In this DVT/PE comparator trial, subgroup analysis revealed that warfarin had numerically better efficacy than edoxaban in patients receiving P-gp inhibitors. Based upon the overall lower exposure to edoxaban in P-gp dose adjusted subjects, both EMA and FDA Office of Clinical Pharmacology (OCP) concluded that the edoxaban 50% dose reduction overcorrected for the difference in exposure.(1,4) Consequently, EMA recommended no edoxaban dose adjustments for patients receiving concomitant therapy with quinidine or verapamil.(3,4) A summary of pharmacokinetic interactions with edoxaban and verapamil concluded that if concurrent use is considered safe.(7) P-gp inhibitors linked to this interaction are: amiodarone, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, daclatasvir, danicopan, daraxonrasib, daridorexant, diltiazem, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, imlunestrant, indinavir, oral itraconazole, ivacaftor, josamycin, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pirtobrutinib, posaconazole, propafenone, quinidine, ranolazine, selpercatinib, sotorasib, telaprevir, telithromycin, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, vepdegestrant, verapamil, vimseltinib, and voclosporin.(8)

Select P-Gp Inhibitors/Edoxaban (> 30 Mg)

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

MECHANISM OF ACTION: Edoxaban is a substrate for P-glycoprotein (P-gp). Inhibitors of P-gp may increase intestinal absorption and decrease renal tubular elimination of edoxaban.(1,2)

CLINICAL EFFECTS: Concurrent use with selected P-gp inhibitors may result in higher systemic concentrations of edoxaban which may increase the risk for bleeding.(1,2)

PREDISPOSING FACTORS: Bleeding risk may be increased in patients with creatinine clearance below 50 mL per minute(1-4). Use of multiple agents which increase edoxaban exposure or affect hemostasis would be expected to increase the risk for bleeding. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: Management recommendations between approving regulatory agencies (FDA or European Medicines Agency, EMA) are conflicting. EMA approved prescribing information specifically states that dosage adjustments are not required solely for concomitant use with amiodarone, quinidine, or verapamil regardless of indication.(3,4) Potential interactions with azithromycin, clarithromycin, or oral itraconazole are not described.(3) FDA approved prescribing recommendations for edoxaban are indication specific:(2) - For prevention of stroke or embolic events due to nonvalvular atrial fibrillation, no edoxaban dose adjustments are recommended during concomitant therapy with P-glycoprotein inhibitors. - For treatment of deep vein thrombosis (DVT) or pulmonary embolism (PE), the edoxaban dose should be reduced to 30 mg daily during concomitant use with azithromycin, clarithromycin, oral itraconazole, quinidine or verapamil. The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to edoxaban.(6) Monitor patients receiving anticoagulant therapy for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. anti Factor Xa inhibition) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. Discontinue edoxaban in patients with active bleeding. The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(9)

DISCUSSION: Edoxaban in vivo interaction studies have been performed for quinidine and verapamil. In vivo interaction studies have not been conducted for the remaining P-gp inhibitors linked to this monograph.(1,4) In an interaction study, the effect of repeat administration of quinidine (300 mg TID) on a single oral dose of edoxaban 60 mg was evaluated in healthy subjects. Both peak (Cmax) and total systemic exposure (AUC) to edoxaban and to the active M4 metabolite increased approximately 1.75-fold.(1) In an interaction study, the effect of repeat administration of verapamil (240 mg Verapamil SR Tablets (Calan SR) QD for 11 Days) on a single oral dose of edoxaban 60 mg on the morning of Day 10 was evaluated in healthy subjects. Total and peak systemic exposure to edoxaban increased 1.53-fold and 1.53-fold, respectively. Total and peak systemic exposure to the active M4 metabolite increased 1.31-fold and 1.28-fold, respectively.(1) Based upon the above results, patients in the DVT/PE trial had a 50% dose reduction (from 60 mg to 30 mg) during concomitant therapy with P-glycoprotein inhibitors. Approximately 0.5% of these patients required a dose reduction solely due to P-gp inhibitor use. This low rate of concurrent therapy was too small to allow for detailed statistical evaluation. Almost all of these patients were receiving quinidine or verapamil. In these patients, both trough edoxaban concentrations (Ctrough) used to evaluate bleeding risk, and total edoxaban exposure (AUC or area-under-curve) used to evaluate treatment efficacy, were lower than patients who did not require any edoxaban dose adjustment. In this DVT/PE comparator trial, subgroup analysis revealed that warfarin had numerically better efficacy than edoxaban in patients receiving P-gp inhibitors. Based upon the overall lower exposure to edoxaban in P-gp dose adjusted subjects, both EMA and FDA Office of Clinical Pharmacology (OCP) concluded that the edoxaban 50% dose reduction overcorrected for the difference in exposure.(1,4) Consequently, EMA recommended no edoxaban dose adjustments for patients receiving concomitant therapy with quinidine or verapamil.(3,4) A summary of pharmacokinetic interactions with edoxaban and verapamil concluded that if concurrent use is considered safe.(7) P-gp inhibitors linked to this interaction are: amiodarone, asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, daclatasvir, danicopan, daraxonrasib, daridorexant, diltiazem, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, imlunestrant, indinavir, oral itraconazole, ivacaftor, josamycin, ledipasvir, lonafarnib, neratinib, osimertinib, pirtobrutinib, posaconazole, propafenone, quinidine, ranolazine, selpercatinib, sotorasib, telaprevir, telithromycin, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, vepdegestrant, verapamil, vimseltinib, and voclosporin.(8)

Selected Kinase Inhibitors/Antacids

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

MECHANISM OF ACTION: The solubility of bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib(8) is pH dependent. Antacid-induced changes in gastric pH may decrease the absorption of these agents.(1-8)

CLINICAL EFFECTS: Simultaneous administration of antacids may result in decreased levels and effectiveness of bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib.(8)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Antacid use should be considered in place of H2 blockers or proton pump inhibitors in patients receiving bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib;(8) however, separation of administration times is required. If antacids are used, separate the administration times by several hours(1-8) but at least 2 hours for bosutinib,(1) dasatinib,(2) nilotinib,(6) and pexidartinib(8), 6 hours for gefitinib,(4) and 3 hours for neratinib.(5) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.

DISCUSSION: In a study in 24 healthy subjects, lansoprazole (60 mg) decreased bosutinib (400 mg single dose) area-under-curve (AUC) and maximum concentration (Cmax) by 26% and 46%, respectively.(1) In a study in 24 healthy subjects, simultaneous administration of dasatinib (50 mg) with aluminum hydroxide/magnesium hydroxide (30 ml) decreased dasatinib AUC and Cmax by 55% and 58%, respectively. In the same subjects, administration of the antacid 2 hours before dasatinib decreased dasatinib Cmax by 26%, but had no effect on dasatinib AUC.(2) In a study in 24 healthy subjects, administration of a single dose of dasatinib (50 mg) 10 hours after famotidine decreased dasatinib AUC and Cmax by 61% and 63%, respectively.(2) In a study, concurrent omeprazole decreased the AUC and Cmax of erlotinib by 46% and 61%, respectively.3) In a study, concurrent esomeprazole decreased the AUC of nilotinib by 34%.(6) In a study in 15 healthy subjects, lansoprazole (30 mg at steady state) decreased the Cmax and AUC of a single dose of neratinib (240 mg) by 71% and 65%, respectively.(5) There were no significant changes in nilotinib pharmacokinetics when famotidine was administered 10 hours before or 2 hours after nilotinib.(6) There were no significant changes in nilotinib pharmacokinetics when an antacid (aluminum hydroxide/magnesium hydroxide/simethicone) was administered 2 hours before or after nilotinib.(6) Coadministration of esomeprazole decreased pexidartinib Cmax and AUC by 55% and 50%, respectively.(8)

Selected P-Glycoprotein (P-Gp) Inhibitors/Betrixaban

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

MECHANISM OF ACTION: Betrixaban is a substrate for the P-glycoprotein (P-gp) system. Inhibition of intestinal P-gp leads to increased absorption of betrixaban.(1)

CLINICAL EFFECTS: The concurrent use betrixaban with P-gp inhibitors may lead to elevated plasma levels of betrixaban, increasing the risk for bleeding.

PREDISPOSING FACTORS: Factors associated with an increased risk for bleeding include renal impairment, concomitant use of P-gp inhibitors, coexisting conditions (e.g. recent trauma) or use of drugs (e.g. NSAIDs) associated with bleeding risk, and patient weight < 50 kg.(1)

PATIENT MANAGEMENT: Assess renal function and evaluate patient for other pre-existing risk factors for bleeding prior to initiating concurrent therapy. The concurrent use of betrixaban and P-gp inhibitors should be avoided in patients with severe renal impairment (CrCl less than 30 ml/min).(1) The recommended dose for patients receiving or starting concomitant P-gp inhibitors is an initial single dose of 80 mg followed by 40 mg once daily. The recommended duration of treatment is 35 to 42 days.(1) Note that if betrixaban is used with the combination of darunavir and cobicistat, dose adjustment of betrixaban is not necessary.(2) The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to betrixaban.(3) Careful monitoring for signs and symptoms of bleeding is warranted during concurrent therapy. Consider regular monitoring of hemoglobin, platelet levels, and/or activated partial thromboplastin time (aPTT) or ecarin clotting time (ECT). Instruct patients to report any signs and symptoms of bleeding, such as bleeding from the eyes, gums or nose; unusual bruising; dark stools; red or dark brown urine; and/or abdominal pain or swelling.(1) The anticoagulant effect of betrixaban is expected to persist for at least 72 hours after the last dose. The manufacturer of daraxonrasib states P-gp substrates should be administered at least 4 hours apart from daraxonrasib.(8)

DISCUSSION: In the APEX randomized, double-blind study the incidence of major or clinically relevant non-major bleeds (CRNM) in the betrixaban 40mg and 80 mg group was higher in patients taking concomitant P-gp inhibitors (2.8% vs. 4.1% vs. 4.7%).(4) In a study in 12 subjects, concomitant administration of a single dose of betrixaban (40 mg) following a 5-day regimen of ketoconazole (200 mg twice daily) resulted in an increase in betrixaban's maximum concentration (Cmax) and area-under-the-curve (AUC) of 2.3-fold and 2.3-fold, respectively.(5) An open-label study looking at concomitant administration of a single dose of betrixaban with verapamil in 18 subjects found an increase in betrixaban's Cmax and AUC of approximately 4.7-fold and 3-fold, respectively.(5) In a study, concomitant administration of betrixaban (80 mg) with amiodarone resulted in an increase in betrixaban's Cmax by 143%.(5) A summary of pharmacokinetic interactions with betrixaban and amiodarone, diltiazem, or verapamil concluded that if concurrent use is warranted, the betrixaban dose should be reduced to 80 mg once then 40 mg daily. Use should be avoided if CrCl is less than 30 ml/min.(6) P-gp inhibitors include asunaprevir, aumolertinib, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, cyclosporine, daclatasvir, danicopan, daraxonrasib, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fostamatinib, ginseng, glecaprevir, hydroquinidine, imlunestrant, indinavir, itraconazole, ivacaftor, josamycin, lapatinib, ledipasvir, lonafarnib, lopinavir, mavorixafor, neratinib, osimertinib, pibrentasvir, pirtobrutinib, posaconazole, propafenone, quinidine, ranolazine, ritonavir, selpercatinib, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, telaprevir, telithromycin, tepotinib, tezacaftor, tucatinib, valbenazine, velpatasvir, vemurafenib, vepdegestrant, vimseltinib, voclosporin and voxilaprevir.(1,4-7)

*None.

• Lactation

• Child-pugh class C hepatic impairment
• Disease of liver
• Pregnancy
• Severe diarrhea

There are no moderate contraindications for this drug.

Adverse effects reported in >=5% of patients receiving neratinib monotherapy include diarrhea, nausea, abdominal pain, abdominal distension, fatigue, vomiting, rash, stomatitis, decreased appetite, nail disorders, dry skin, muscle spasms, epistaxis, decreased weight, increased AST or ALT, urinary tract infections, and dyspepsia.

Adverse effects reported in >=5% of patients receiving neratinib in combination with capecitabine include diarrhea, nausea, vomiting, decreased appetite, constipation, fatigue, decreased weight, dizziness, back pain, arthralgia, urinary tract infection, upper respiratory tract infection, abdominal distension, renal impairment, and muscle spasms.

More Frequent

• Diarrhea
• Increased alanine transaminase
• Increased aspartate transaminase

Less Frequent

• Abnormal hepatic function tests
• Dehydration
• Hyperbilirubinemia
• Skin fissure

Rare or Very Rare

• Renal failure

More Frequent

• Abdominal distension
• Acute abdominal pain
• Anorexia
• Dry skin
• Dyspepsia
• Fatigue
• Muscle spasm
• Nail disorders
• Nausea
• Skin rash
• Stomatitis
• Urinary tract infection
• Vomiting
• Weight loss

Less Frequent

• Dizziness
• Epistaxis
• Hypotension
• Xerostomia

Rare or Very Rare

• Acneiform eruption
• Cellulitis
• Cheilitis
• Erysipelas
• Glossitis
• Nail discoloration
• Onychoclasis
• Paronychia
• Pruritus of skin
• Skin inflammation
• Sore tongue

No enhanced messaging available.

Safety and efficacy of neratinib have not been established in pediatric patients.

Neratinib may cause fetal harm if administered to pregnant women based on its mechanism of action and animal findings. (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

It is not known whether neratinib or its metabolites are distributed into milk. Because of the potential for serious adverse reactions to neratinib in nursing infants, women should be advised to discontinue nursing while receiving neratinib and for at least 1 month after the drug is discontinued. The effects of the drug or its metabolites on nursing infants or on the production of milk are unknown.

There are currently no specific dosage recommendations for geriatric patients.

In the ExteNET study, 12% of patients receiving neratinib in the safety population were >=65 years of age and 1.8% were >=75 years of age. Patients >=65 years of age had higher incidences of discontinuance of neratinib due to adverse reactions but similar incidences of serious adverse reactions (e.g., vomiting, diarrhea, renal failure, dehydration) compared with younger adults.

In the NALA study, 20% of patients receiving neratinib plus capecitabine in the safety population were >=65 years of age and 4% were >=75 years of age. The incidence of serious adverse reactions was similar between patients >=65 years of age and younger patients; the most commonly reported serious adverse events in geriatric patients were diarrhea, acute kidney injury, and dehydration. No overall differences in efficacy were noted between patients >=65 years of age and those <65 years of age.