Oravig (miconazole)

No dosing information is available for this tab.

Miconazole nitrate is administered topically as a cream, powder, or aerosol powder or tincture, or intravaginally as a vaginal cream or suppository. Miconazole powder or aerosol powder are not recommended for use on the scalp or nails.

No dosing information is available for this tab.

There is no enhanced messaging for this drug.

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

Fluconazole; Miconazole/Cisapride

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: Inhibition of metabolism of cisapride by azole antifungal agents by CYP3A4.(1)

CLINICAL EFFECTS: Increased serum concentrations of cisapride resulting in possible life-threatening cardiotoxicity, including prolongation of the QT interval.

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.(7) 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 inhibitors its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(7)

PATIENT MANAGEMENT: Concomitant administration of fluconazole or miconazole with cisapride is contraindicated.

DISCUSSION: Elevated plasma levels of cisapride can cause QT prolongation and torsades de pointes-type ventricular tachycardia which may be fatal. Ketoconazole is contraindicated with concurrent administration of cisapride because ketoconazole has resulted in markedly elevated cisapride serum levels and prolonged QT interval. Serious cardiovascular events, including QT prolongation, torsades de pointes, ventricular tachycardia, cardiac arrest, and/or sudden death have been reported in patients taking cisapride in combination with itraconazole and/or other CYP P-450-3A4 inhibitors.(3) Cisapride is metabolized by CYP3A4. In vitro studies have shown itraconazole, miconazole, posaconazole, and voriconazole to be potent inhibitors of CYP3A4 and like ketoconazole, these agents are also expected to markedly increase cisapride serum concentrations. One or more of the drug pairs linked to this monograph have been included in a list of interactions that should be considered "high-priority" for inclusion and should not be inactivated in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.

Misc Antifungal Agents/Astemizole; Terfenadine

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: Fluconazole, itraconazole, ketoconazole, posaconazole, and voriconazole inhibit the metabolism of astemizole and terfenadine.

CLINICAL EFFECTS: Increased serum levels of astemizole and terfenadine with possibly increased side effects including life-threatening cardiac arrhythmias such as QT prolongation or torsades de pointes. Fatalities have been reported from the combination of azole antifungals with astemizole and terfenadine.

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.(23) 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).(22)

PATIENT MANAGEMENT: Until further clinical data are available, because of the potential seriousness of this possible interaction, avoid concomitant administration of these drugs. The concurrent use of terfenadine or astemizole and ketoconazole or itraconazole is contraindicated according to package labeling. The concurrent use of fluconazole at doses of 400 mg per day or greater with terfenadine is contraindicated. Concurrent therapy with fluconazole doses of less than 400 mg per day with terfenadine should be carefully monitored. The manufacturer of voriconazole states that concurrent administration with astemizole or terfenadine is contraindicated. The concurrent use of posaconazole and either astemizole or terfenadine is contraindicated. Fexofenadine, desloratadine, and loratadine, nonsedating antihistamines which have been shown to have no effects on cardiac function, may be alternative in patients receiving azole antifungals. If concurrent therapy is deemed medically necessary, 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: Cardiac toxicity (torsades de pointes, a form of polymorphic ventricular tachycardia associated with prolongation of the QT interval) was reported in a 39-year old woman taking terfenadine and ketoconazole concomitantly.(1) Plasma terfenadine levels were higher than expected for a patient receiving 60 mg twice daily. When electrocardiograms from patients receiving terfenadine and ketoconazole concurrently were compared with electrocardiograms from patients receiving only ketoconazole, a 10 to 20 millisecond prolongation in the corrected QT interval was found at times of high, unchanged terfenadine levels and lower than normal levels of the acid metabolite.(3) One study of concurrent therapy with fluconazole 200 mg daily did not show a prolongation of the QTc interval, while another study with fluconazole dosages of 400 mg and 800 mg daily showed significant increases in plasma levels of terfenadine.(13) In a study in 24 healthy subjects, concurrent ketoconazole (400 mg daily) and fexofenadine (120 mg twice daily) increased the fexofenadine maximum concentration (Cmax) and area-under-curve (AUC) by 135% and 164%, respectively. However, there were no changes in adverse effects or QTc interval.(14)

Strong & Moderate Cyp2c9 Inhibitors/Deuruxolitinib

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

MECHANISM OF ACTION: Strong or moderate CYP2C9 inhibitors may inhibit the metabolism of deuruxolitinib.(1)

CLINICAL EFFECTS: Concurrent use of deuruxolitinib with a strong or moderate inhibitor of CYP2C9 may result in elevated levels of and toxicity from deuruxolitinib, including hematologic toxicities (neutropenia, lymphopenia, anemia), lipid abnormalities, infection, and thrombosis.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of deuruxolitinib states that concomitant treatment with a strong or moderate CYP2C9 inhibitor is contraindicated.(1)

DISCUSSION: Concurrent use with strong CYP2C9 inhibitors has not been studied. Based on pharmacokinetic modelling, deuruxolitinib area-under-curve (AUC) is predicted to be increased by 200% and maximum concentration (Cmax) by 25% following concomitant use of multiple dosages of a strong CYP2C9 inhibitor with a single dose of 12 mg deuruxolitinib (1.5 times the licensed 8 mg dose).(1) Deuruxolitinib AUC increased by 140% and Cmax by 21% following concomitant use of multiple dosages of 200 mg fluconazole (dual moderate CYP3A4 and CYP2C9 inhibitor) with a single dose of 12 mg deuruxolitinib (1.5 times the licensed 8 mg dose).(1) Strong CYP2C9 inhibitors linked to this monograph include: camizestrant and sulfaphenazole.(2-3) Moderate CY2C9 inhibitors linked to this monograph include: amiodarone, apazone, benzbromarone, fluconazole, miconazole, mifepristone, milk thistle, nitisinone, oxandrolone, phenylbutazone, and piperine.(2-3)

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

Miconazole/Sulfonylureas

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

MECHANISM OF ACTION: Sulfonylureas are sensitive CYP2C9 substrates. Miconazole is a moderate CYP2C9 inhibitor and may inhibit the metabolism of sulfonylureas.(1)

CLINICAL EFFECTS: Concurrent use of miconazole may result in elevated levels and effects of the sulfonylureas, including severe hypoglycemia and coma.(2-4)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The Australian, Canadian, and UK manufacturers of gliclazide and the UK manufacturer of glipizide state that concurrent use with miconazole via systemic routes or oro-mucosal gel is contraindicated.(2-5) The manufacturers of other sulfonylureas and the Australian and UK manufacturers of miconazole advise caution when using the combination of sulfonylureas and miconazole. Monitor blood glucose levels during concurrent therapy. The dose of the sulfonylurea may need to be adjusted.(6-15)

DISCUSSION: A French pharmacovigilance study found that 98 cases of sulfonylurea-induced hypoglycemia were reported between 1985-1990, mostly with gliclazide (46 cases) and glyburide (40 cases). Miconazole was one of the most frequent causes of drug interactions (8 cases).(16) Other cases of severe hypoglycemia after miconazole was started in patients on sulfonylureas have been reported.(17-18)

Select Azole Antifungal Agents/Coumarin Anticoagulants

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

MECHANISM OF ACTION: The more potent warfarin S-enantiomer is metabolized by CYP2C9 while the weaker R-enantiomer is metabolized by CYP1A2 and CYP3A4. Miconazole is a moderate-strong inhibitor of CYP2C9; fluconazole is a moderate inhibitor of CYP2C9 and CYP3A4; voriconazole and ketoconazole are both weak inhibitors of CYP2C9 and strong inhibitors of CYP3A4.

CLINICAL EFFECTS: Concurrent use of select azole antifungals and coumarin anticoagulants may increase the risk for bleeding.

PREDISPOSING FACTORS: The antifungal dose and inhibitory potency, particularly for CYP2C9, are drug factors which affect the magnitude of this interaction. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Additional 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). Azole antifungal inhibition of CYP2C9, may increase the risk of conversion to the CYP2C9 poor metabolizer phenotype. Patients with CYP2C9 intermediate metabolizer genotype are expected to be the most susceptible to this phenoconversion. Patients with a pre-existing CYP2C9 poor metabolizer genotype would be less susceptible to this interaction. However, patients with reduced function genotypes (e.g. CYP2C9 *1/*3, *2/*2, *2/*3, and *3/*3) have an inherently higher risk for bleeding at usual anticoagulant doses and thus generally require lower doses to achieve effective and safe anticoagulation. In addition, CYP2C9 poor metabolizers require more a prolonged time (>2 to 4 weeks) to achieve maximum INR effect for a given dosage regimen than patients without these CYP2C9 variants.

PATIENT MANAGEMENT: In patients receiving warfarin when fluconazole, voriconazole, miconazole or ketoconazole is started, anticipate the need for a dose reduction. Check the baseline INR then closely monitor and adjust the dose of warfarin until the INR has stabilized on the combination. After the azole therapy is discontinued, close monitoring is again needed as the INR may fall after removal of the inhibitor. If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. 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 time of highest risk for a coumarin-type drug interaction is when the precipitant drug is initiated or discontinued. Contact the prescriber before initiating, altering the dose or discontinuing either drug.

DISCUSSION: Selected azole antifungal agents can cause an increase in the anticoagulant effects of warfarin. The drug-related risk is dependent on the specific azole, dose and route. A large systematic review was performed on 72 warfarin drug-drug interactions studies that reported on bleeding, thromboembolic events, or death. Most studies were retrospective cohorts. A meta-analysis of 11 of those studies found a higher rate of clinically significant bleeding in patients on warfarin and antimicrobials (OR=1.63; 95% CI 1.45-1.83). Increased bleeding risk was also seen in subgroup analyses with azole antifungals (OR=1.86; 95% CI 1.40-2.47). A retrospective review compared the changes in warfarin effects with coadministration of fluconazole, itraconazole, or voriconazole in 18, 6, and 5 patients, respectively. Mean INR increased from 1.4 to 2.94 in patients taking fluconazole (p<0.001) and increased >20% in 15 out of 18 patients. Mean INR increased from 1.95 to 2.89 in patients taking voriconazole (p<0.05) and increased >20% in 4 out of 5 patients. Mean INR increased slightly from 1.86 to 1.92 in patients taking itraconazole (p=0.37) and did not increase >20% in any patient. In healthy subjects, the administration of voriconazole (300 mg every 12 hours for 12 days) prior to warfarin (30 mg single dose) doubled the prothrombin time when compared to warfarin plus placebo. A large epidemiologic study evaluated the risk for hospitalization due to gastrointestinal (GI) bleeding in warfarin patients treated with or without various anti-infective agents, including fluconazole. Warfarin patients treated with fluconazole had an approximately 2-fold increase in risk for hospitalization due to a GI bleed compared with warfarin patients without infection or warfarin patients receiving alternative anti-infective treatment (e.g. cephalexin, amoxicillin). This risk was highest in patients who received fluconazole 6 to 15 days prior to admission, leading authors to suggest this risk was due to a pharmacokinetic interaction between warfarin and fluconazole, and not due to infection or infection sequelae (e.g. change in diet or gut bacteria). A drug-drug interaction study was performed to evaluate the effect of a single 150 mg dose of fluconazole on prothrombin times in 6 women who had received warfarin therapy for at least 6 months and had stable, therapeutic INRs. Three of 6 women had an INR > 4 or had a bleeding episode: one woman had an INR of 4.6 on day 2, one woman had an INR of 5.2 on day 5, and one woman developed a subconjunctival hemorrhage in the absence of trauma or physical straining on day 6 (INR = 3.4). Miconazole is the most potent known CYP2C9 inhibitor in vivo. In an interaction study in 6 healthy volunteers, oral miconazole 125 mg daily for 18 days increased warfarin exposure (AUC, area-under-curve) 4.7-fold. Black stools have been reported with warfarin and administration of miconazole oral gel. Documentation for oral ketoconazole is less conclusive. However, as ketoconazole is considered a moderate CYP2C9 inhibitor an interaction with warfarin would be expected.

Selected Azole Antifungal Agents/Selected Immunosuppressants

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

MECHANISM OF ACTION: The metabolism of cyclosporine, sirolimus, and temsirolimus by CYP3A4 may be inhibited by clotrimazole, isavuconazonium, itraconazole, and ketoconazole.

CLINICAL EFFECTS: Concurrent administration of an azole antifungal may result in elevated levels of and toxicity from cyclosporine, sirolimus, or temsirolimus.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Cyclosporine, sirolimus, or temsirolimus levels and renal function should be monitored if an azole antifungal is initiated or discontinued from concurrent therapy. The dosage of cyclosporine, sirolimus, or temsirolimus may need to be adjusted. Guidelines from the American Society of Transplantation recommend avoiding concurrent use of cyclosporine with itraconazole or ketoconazole. If the combination must be used, lower the dose of the immunosuppressant by at least 50 % and monitor levels closely.(42) The American Society of Transplantation guidelines state that concurrent use of sirolimus is contraindicated with ketoconazole and is not recommended with itraconazole.(42) The manufacturer of sirolimus states that the concurrent use of itraconazole or ketoconazole is not recommended and should be avoided,(25) while the US manufacturer of itraconazole states that concurrent therapy with sirolimus or temsirolimus (IV) is not recommended during and two weeks after itraconazole treatment.(41) The US manufacturer of temsirolimus recommends that concurrent therapy with strong CYP3A4 inhibitors such as itraconazole or ketoconazole be avoided. If concurrent use is warranted, a dosage reduction to 12.5 mg/week of temsirolimus should be considered. If the azole is discontinued, a washout period of 1 week should be allowed before adjusting the dosage of temsirolimus to previous levels.(27) The US manufacturer of sirolimus protein-bound injection (Fyarro) states a dose reduction to 56 mg/m2 is recommended when used concurrently with moderate or weak CYP3A4 inhibitors. Concurrent use with strong CYP3A4 inhibitors should be avoided.(44)

DISCUSSION: Clotrimazole, fluconazole, itraconazole and ketoconazole have been reported to increase cyclosporine concentrations although the documentation is most supportive of the interaction with ketoconazole. Exercise caution when stopping the antifungal agent as cyclosporine concentration may decrease. Concurrent isavuconazonium increased the area-under-curve (AUC) of cyclosporine (300 mg) by approximately 1.3-fold. There have been several case reports of increased sirolimus levels with concurrent fluconazole and itraconazole therapy and decreased levels of sirolimus after discontinuation of itraconazole. Concurrent isavuconazonium increased the maximum concentration (Cmax) and AUC of sirolimus (2 mg) by approximately 1.6-fold and 1.8-fold, respectively. In a multiple-dose study, concomitant administration of ketoconazole with sirolimus oral solution increased the sirolimus Cmax, time to Cmax (Tmax), and AUC by 4.3-fold, 38%, and 10.9-fold, respectively. Single-dose sirolimus did not affect steady-state 12-hour plasma ketoconazole concentrations. In a study in 6 patients, ketoconazole was successfully used to augment sirolimus levels. Patients were able to receive one-eight to one-fourth (0.25 - 0.50 mg daily) of the usual sirolimus dose while taking 100 to 200 mg of ketoconazole daily. Concurrent administration of ketoconazole had no effects on temsirolimus AUC or Cmax; however, sirolimus AUC and Cmax increased 3.1-fold and 2.2-fold, respectively. Dosage adjustment of temsirolimus to 12.5 mg/week in the presence of strong CYP3A4 inhibitors is expected to adjust levels to the range observed without inhibitors; however, there are no data available with this dose adjustment.

Selected Azole Antifungal Agents/Tacrolimus

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

MECHANISM OF ACTION: The metabolism of tacrolimus by CYP3A4 may be inhibited by clotrimazole, itraconazole, and ketoconazole.

CLINICAL EFFECTS: Concurrent administration of an azole antifungal may result in elevated levels of and toxicity from tacrolimus, including QT prolongation, nephrotoxicity, neurotoxicity, cardiovascular toxicity, hypertension, anemia, and increased risk of serious infections.

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. 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).

PATIENT MANAGEMENT: Tacrolimus levels and renal function should be monitored if an azole antifungal is initiated or discontinued from concurrent therapy. The dosage of tacrolimus may need to be adjusted. Guidelines from the American Society of Transplantation recommend avoiding concurrent use of tacrolimus with itraconazole or ketoconazole. If the combination must be used, lower the dose of the immunosuppressant by at least 50% and monitor levels closely. The US manufacturer of tacrolimus states that coadministration with strong CYP3A4 inhibitors may result in a rapid and sharp rise in tacrolimus concentration despite immediate tacrolimus dose reduction. Frequent monitoring of tacrolimus levels should start within 1-3 days of initiation of concurrent therapy and continue as necessary. 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: The interaction between fluconazole and tacrolimus is dose-dependent. In a study in 20 patients, the addition of fluconazole to tacrolimus therapy resulted in the need for a 56% dosage reduction in tacrolimus. Patients on fluconazole 100 mg/day experienced a 1.4-fold increase in tacrolimus trough level and those on fluconazole 200 mg/day had a 3.1-fold increase in tacrolimus troughs. Acute renal dysfunction was seen in three patients and acute mental status changes were seen in two subjects. Another study found a 16% increase in tacrolimus levels with concurrent fluconazole. In a case report of a patient who is homozygous for a loss-of-function allele for CYP3A5, fluconazole increased tacrolimus levels by 9.13-fold and required an 87% reduction in tacrolimus dose. In a study in six subjects, the administration of ketoconazole ten hours before tacrolimus did not significantly affect the clearance, volume of distribution, or hepatic bioavailability of tacrolimus. However, there was 100% increase in oral bioavailability of tacrolimus when administered ten hours after ketoconazole. In a study in six subjects, concurrent administration of ketoconazole (200 mg) increased tacrolimus oral bioavailability by 114%. Oral tacrolimus clearance decreased by 65.6%. There was no significant effect on the clearance of intravenous tacrolimus. In a retrospective study of lung transplant patients, those who had itraconazole discontinued while on tacrolimus required a 76% increase in dose to maintain therapeutic levels, (p < 0.0001). There have been several case reports of increased tacrolimus levels during the concurrent administration of clotrimazole, itraconazole, and ketoconazole.

Selected Cyp3a4 Inhibitor/Tolterodine (>1 Mg Ir Or >2 Mg Er)

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

MECHANISM OF ACTION: Cyclosporine, erythromycin, miconazole, and vinblastine may inhibit the metabolism of tolterodine by CYP3A4.(1,2)

CLINICAL EFFECTS: The concurrent administration of tolterodine with cyclosporine, erythromycin, miconazole, or vinblastine may result in elevated levels of tolterodine and signs of toxicity.(1,2)

PREDISPOSING FACTORS: Patients who are CYP2D6 poor metabolizers may be at increased risk.(1,2) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(4)

PATIENT MANAGEMENT: The manufacturer of tolterodine recommends that a maximum tolterodine dosage of 1 mg twice daily of the non extended release dosage form(1) or 2 mg once daily of the extended release dosage form(2) be used in patients receiving concurrent therapy with cyclosporine, erythromycin, miconazole, or vinblastine. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a study in eight subjects who were deficient in CYP2D6, the concurrent administration of tolterodine (2 mg) with ketoconazole (200 mg once daily for four days), another inhibitor of CYP3A4, resulted in a 60% decrease in tolterodine clearance.(5) Tolterodine AUC and Cmax increased 2.5-fold and 2-fold, respectively.(2) In a study of the effect of tolterodine immediate release tablets, the effect on the QT interval appeared greater for 8 mg/day (two times the therapeutic dose) compared to 4 mg/day. Tolterodine 2 mg BID and tolterodine 4 mg BID increased the QTcF by 5.01 msec (0.28-9.74 msec) and 11.84 msec (7.11-16.58 msec), respectively. The change in QT interval was more pronounced in CYP2D6 poor metabolizers (PM) than extensive metabolizers (EMs).(1,2)

Strong And Moderate Cyp2c9 Inhibitors/Bosentan

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

MECHANISM OF ACTION: Bosentan is metabolized by CYP2C9 and CYP3A4. It is also an inducer of these enzymes. With regular dosing bosentan auto-induces its own metabolism.(1) Strong and moderate CYP2C9 inhibitors may inhibit the CYP2C9 mediated metabolism of bosentan.(1-2)

CLINICAL EFFECTS: Concurrent use of bosentan with an inhibitor of CYP2C9 may result in elevated levels of and toxicity from bosentan.(1)

PREDISPOSING FACTORS: Concurrent use of bosentan, a CYP2C9 inhibitor and a CYP3A4 inhibitor could lead to blockade of both major metabolic pathways for bosentan, resulting in large increases in bosentan plasma concentrations.

PATIENT MANAGEMENT: Review medication list to see if patient is also receiving a CYP3A4 inhibitor (e.g. aprepitant, boceprevir, ceritinib, ciprofloxacin, clarithromycin, conivaptan, crizotinib, cyclosporine, darunavir, diltiazem, dronedarone, erythromycin, fluconazole, fosaprepitant, idelalisib, imatinib, isavuconazole, itraconazole, ketoconazole, letermovir, mibefradil, nefazodone, netupitant, nilotinib, posaconazole, ribociclib, telaprevir, telithromycin, troleandomycin, verapamil, and voriconazole). Concomitant use of both a CYP2C9 and CYP3A4 inhibitor is not recommended by the manufacturer as the combination may lead to large increases in bosentan plasma concentrations.(1) For patients stabilized on bosentan when a CYP2C9 inhibitor is initiated, monitor tolerance to concomitant therapy and adjust bosentan dose if needed. The manufacturer of nitisinone recommends reducing the dosage of a CYP2C9 substrate like bosentan by one-half.(3)

DISCUSSION: Concurrent use with CYP2C9 inhibitors has not been studied. In a study in healthy subjects, concurrent bosentan and ketoconazole (a strong CYP3A4 inhibitor) increased bosentan steady-state maximum concentrations (Cmax) and area-under-curve (AUC) by 2.1-fold and 2.3-fold, respectively.(2) Strong CYP2C9 inhibitors linked to this monograph include: miconazole.(4) Moderate CYP2C9 inhibitors linked to this monograph include: amiodarone, apazone, asciminib, benzbromarone, nitisinone, oxandrolone, piperine, sulfaphenazole, and phenylbutazone.(4)

Strong Cyp3a4 Or Strong & Moderate Cyp2c9 Inhib/Erdafitinib

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

MECHANISM OF ACTION: Erdafitinib is metabolized by CYP3A4 and CYP2C9. Strong inhibitors of CYP3A4 or moderate inhibitors of CYP2C9 may inhibit the metabolism of erdafitinib.(1)

CLINICAL EFFECTS: Concurrent use of strong CYP3A4 or moderate CYP2C9 inhibitors may increase the levels and effects of erdafitinib, including retinopathy and hyperphosphatemia.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US prescribing information states that concurrent use of erdafitinib with strong CYP3A4 inhibitors or moderate CYPC9 inhibitors should be avoided. If concurrent use cannot be avoided, monitor closely for adverse reactions and consider a dose modification based on prescribing information. If the strong CYP3A4 or moderate CYP2C9 inhibitor is discontinued, consider increasing the erdafitinib dose if patient does not have any drug-related toxicity.(1) If concurrent use with nitisinone cannot be avoided, the manufacturer of nitisinone recommends reducing the dosage of a CYP2C9 substrate like erdafitinib by one-half.(2)

DISCUSSION: In PKPB models, concurrent use of fluconazole (a moderate CYP2C9 and CYP3A4 inhibitor) resulted in erdafitinib mean ratios for concentration maximum (Cmax) and area-under-curve (AUC) of 121% and 148% , respectively, compared to erdafitinib alone.(1) In PKPB models, concurrent use of itraconazole (a strong CYP3A4 inhibitor and P-gp inhibitor) resulted in erdafitinib mean ratios for Cmax and AUC of 105% and 134%, respectively, compared to erdafitinib alone.(1) Strong inhibitors of CYP3A4 include: adagrasib, boceprevir, ceritinib, clarithromycin, cobicistat, ensitrelvir, idelalisib, indinavir, itraconazole, josamycin, ketoconazole, levoketoconazole, lonafarnib, lopinavir, mibefradil, mifepristone, nefazodone, nelfinavir, nirmatrelvir, paritaprevir, posaconazole, relacorilant, ribociclib, saquinavir, telaprevir, telithromycin, tipranavir, troleandomycin, tucatinib, and voriconazole.(3,4) Strong CYP2C9 inhibitors include: camizestrant.(3,4) Moderate inhibitors of CYP2C9 include: adagrasib, amiodarone, apazone, asciminib, benzbromarone, fluconazole, miconazole, mifepristone, milk thistle, nitisinone, oxandrolone, phenylbutazone, and sulfaphenazole.(3,4)

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

Moderate Cyp2c9 Inhibitors/Lesinurad

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

MECHANISM OF ACTION: Moderate inhibitors of CYP2C9 may inhibit the metabolism of lesinurad.(1)

CLINICAL EFFECTS: Concurrent use of moderate inhibitors of CYP2C9 may result in elevated levels and toxicity from lesinurad, include nephrotoxicity.(1)

PREDISPOSING FACTORS: Patients with decreased renal function (CrCl less than 60 ml/min) and patients not receiving a xanthine oxidase inhibitor may be at increased risk of nephrotoxicity.(1)

PATIENT MANAGEMENT: Approach the concurrent use of lesinurad and moderate inhibitors of CYP2C9 with caution.(1) Monitor renal function in patients receiving concurrent therapy closely. Interrupt therapy and measure serum creatinine promptly in patients who report flank pain and/or nausea/vomiting.

DISCUSSION: Fluconazole (200 mg daily), a moderate inhibitor of CYP2C9, increased lesinurad levels by 50%.(1)

Selected Cyp2c9 Inhibitors/Selected Nsaids

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

MECHANISM OF ACTION: The major metabolic pathway for many non-steroidal anti-inflammatory agents (NSAIDs) is CYP2C9. Inhibitors of CYP2C9 include: amiodarone, asciminib, diosmin, fluconazole, ketoconazole, miconazole, nitisinone, oxandrolone, piperine, voriconazole, and zafirlukast.(1,2)

CLINICAL EFFECTS: Concurrent use of NSAIDs with inhibitors of CYP2C9 may result in increased levels of and adverse effects from NSAIDs, including increased risk for bleeding. NSAIDs linked to this monograph are celecoxib, diclofenac, flurbiprofen, ibuprofen, meloxicam, naproxen, parecoxib, piroxicam and valdecoxib.

PREDISPOSING FACTORS: Higher doses of either agent would be expected to increase the risk for serious adverse effects such as gastrointestinal bleeding (GIB) or renal failure. Patients who smoke, are elderly, debilitated, dehydrated, have renal impairment, or who have a history of GIB due to NSAIDs are also at increased risk for serious adverse events.(3-7) 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: Patients on routine NSAID therapy when an inhibitor of CYP2C9 is started should be evaluated for patient-specific risk factors for NSAID toxicity. Based upon this risk assessment, consider dose reduction of the NSAID or close monitoring for adverse effects. For a patient already receiving a CYP2C9 inhibitor when an NSAID is started, consider initiating the NSAID at a lower than usual dose, particularly when predisposing risk factors for harm are present. The manufacturer of celecoxib recommends that celecoxib be introduced at the lowest recommended dose in patients receiving fluconazole therapy.(3) The manufacturer of fluconazole states that half the dose of celecoxib may be necessary when fluconazole is added.(4) It would be prudent to follow this recommendation with other CYP2C9 inhibitors and to decrease the dose of celecoxib in patients in whom CYP2C9 inhibitors are added to celecoxib therapy. The manufacturer of diclofenac-misoprostol states that the total daily dose of diclofenac should not exceed the lowest recommended dose of 50 mg twice daily in patients taking CYP2C9 inhibitors.(5) It would be prudent to use the lowest recommended dose of other diclofenac formulations in patients taking CYP2C9 inhibitors. The manufacturer of parecoxib states that the dose of parecoxib should be reduced in those patients who are receiving fluconazole therapy.(6) It would be prudent to follow this recommendation with other CYP2C9 inhibitors. The manufacturer of nitisinone recommends reducing the dosage of a CYP2C9 substrate by one-half.(7) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, 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. 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.

DISCUSSION: The concomitant administration of celecoxib and fluconazole (200 mg daily) resulted in a 2-fold increase in celecoxib plasma concentration.(3) In vitro studies in human hepatocytes found that amiodarone inhibited diclofenac metabolism.(8) In two separate studies, single doses of diclofenac (50 mg) or ibuprofen (400 mg) were coadministered with the last dose of voriconazole (400 mg q12h on Day 1, followed by 200 mg q12h on Day 2). Voriconazole increased the mean AUC of diclofenac by 78% and increased the AUC of the active isomer of ibuprofen by 100%.(9-11) Coadministration of diosmin increased diclofenac levels by 63%.(2) Coadministration of flurbiprofen or ibuprofen with fluconazole increased the AUC of flurbiprofen by 81% and of the active ibuprofen by 82% compared with either agent alone.(4) Concurrent voriconazole increased meloxicam AUC by 47%.(12,13) The concurrent administration of fluconazole and parecoxib resulted in increases in the area-under-curve (AUC) and maximum concentration (Cmax) of valdecoxib (the active metabolite of parecoxib) by 62% and 19%, respectively.(6) In a study, single dose diclofenac (50mg) given concurrently with the last dose of voriconazole (400 mg every 12 hours on Day 1, 200 mg every 12 hours on Day 2) increased Cmax and AUC by 2.1-fold and 1.8-fold, respectively. (5) Inhibitors of CYP2C9 include: amiodarone, asciminib, camizestrant, diosmin, fluconazole, ketoconazole, miconazole, nitisinone, oxandrolone, piperine, voriconazole, and zafirlukast.(1,2)

Selected Cyp3a4 Inhibitors/Tolterodine (<=1 Mg Or <=2 Mg Er)

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

MECHANISM OF ACTION: Cyclosporine, erythromycin, miconazole, and vinblastine may inhibit the metabolism of tolterodine by CYP3A4.(1,2)

CLINICAL EFFECTS: The concurrent administration of tolterodine with cyclosporine, erythromycin, miconazole, or vinblastine may result in elevated levels of tolterodine and signs of toxicity.(1,2)

PREDISPOSING FACTORS: Patients who are CYP2D6 poor metabolizers may be at increased risk.(1,2) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(4)

PATIENT MANAGEMENT: The manufacturer of tolterodine recommends that a maximum tolterodine dosage of 1 mg twice daily of the non extended release dosage form(1) or 2 mg once daily of the extended release dosage form(2) be used in patients receiving concurrent therapy with cyclosporine, erythromycin, miconazole, or vinblastine. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a study in eight subjects who were deficient in CYP2D6, the concurrent administration of tolterodine (2 mg) with ketoconazole (200 mg once daily for four days), another inhibitor of CYP3A4, resulted in a 60% decrease in tolterodine clearance.(5) Tolterodine AUC and Cmax increased 2.5-fold and 2-fold, respectively.(2) In a study of the effect of tolterodine immediate release tablets, the effect on the QT interval appeared greater for 8 mg/day (two times the therapeutic dose) compared to 4 mg/day. Tolterodine 2 mg BID and tolterodine 4 mg BID increased the QTcF by 5.01 msec (0.28-9.74 msec) and 11.84 msec (7.11-16.58 msec), respectively. The change in QT interval was more pronounced in CYP2D6 poor metabolizers (PM) than extensive metabolizers (EMs).(1,2)

Selected Moderate Cyp2c9 Inhibitors/Siponimod

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

MECHANISM OF ACTION: Inhibitors of CYP2C9 may inhibit the metabolism of siponimod.(1)

CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP2C9 may result in elevated levels of and clinical effects of siponimod, including immunosuppression and increased risk of infection.(1) Concurrent use of siponimod with immunosuppressive or immune-modulating agents, such as asciminib, may result in an additive risk and increased risk of serious infections.

PREDISPOSING FACTORS: Concurrent use of a strong or moderate inhibitor of CYP3A4 may increase the effects of the interaction.

PATIENT MANAGEMENT: Monitor for adverse reactions during concomitant use of siponimod with moderate CYP2C9 inhibitors or moderate CYP2C9 and CYP3A4 dual inhibitors.(1) Review the patient's therapy for concurrent use of strong or moderate inhibitors of CYP3A4 prior to initiating siponimod. If concurrent use is necessary, the manufacturer of nitisinone recommends reducing the dosage of a CYP2C9 substrate like siponimod by one-half.(2)

DISCUSSION: Siponimod is metabolized by CYP2C9 (79.3%) and CYP3A4 (18.5%). Concurrent use of fluconazole (a dual moderate inhibitor of CYP2C9 and CYP3A4, 200 mg at steady state) in healthy subjects with the CYP2C9*1/*1 genotype increased the area-under-curve (AUC) of siponimod (4 mg single dose) by 2-fold. Siponimod half-life increased by 50%. Fluconazole increased siponimod AUC by 2-fold to 4-fold across all CYP2C9 genotypes.(1) Selected moderate CYP2C9 inhibitors linked to this monograph include: apazone, asciminib, benzbromarone, felbamate, miconazole, milk thistle, nitisinone, oxandrolone, phenylbutazone, piperine, silibinin, and sulfaphenazole.(3)

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There are no contraindication contraindications for this drug.

There are no severe contraindications for this drug.

• Disease of liver

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Less Frequent

• Skin rash

Rare or Very Rare

• Anaphylaxis

More Frequent

• Diarrhea
• Headache disorder
• Mouth irritation

Less Frequent

• Cough
• Dysgeusia
• Fatigue
• Gingival pain
• Nausea
• Sore tongue
• Toothache
• Upper abdominal pain
• Vomiting
• Xerostomia

Rare or Very Rare

• Pruritus of skin

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No enhanced messaging available.

Because small amounts of miconazole nitrate are absorbed from the vagina, the manufacturer states that the vaginal preparations should not be used in the first trimester of pregnancy unless the drug is considered essential to the welfare of the patient. For self-medication, miconazole nitrate vaginal suppositories or vaginal cream should not be used in pregnant women unless otherwise instructed by a physician. Follow-up reports from clinical studies during which miconazole vaginal preparations were used for up to 14 days in pregnant women have revealed no adverse effects or complications attributable to therapy with the drug in infants born to these women. Prolonged gestation has occurred in rats, but not in rabbits, receiving oral miconazole nitrate. In addition, fetotoxicity and embryotoxicity have occurred in rats and rabbits and dystocia in rats in reproduction studies using oral miconazole nitrate dosages of 80 mg/kg and higher; these effects were not observed in rats following intravaginal administration of the drug.

It is not known whether miconazole nitrate is distributed into milk. Miconazole nitrate should be used with caution in nursing women.

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