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Ketoconazole (Systemic)

Medically reviewed by Drugs.com. Last updated on Sep 23, 2020.

Pronunciation

(kee toe KOE na zole)

Index Terms

  • Nizoral

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Generic: 200 mg

Pharmacologic Category

  • Antifungal Agent, Imidazole Derivative
  • Antifungal Agent, Oral

Pharmacology

Alters the permeability of the cell wall by blocking fungal cytochrome P450; inhibits biosynthesis of triglycerides and phospholipids by fungi; inhibits several fungal enzymes that results in a build-up of toxic concentrations of hydrogen peroxide; for management of prostate cancer, ketoconazole inhibits androgen synthesis

Distribution

Well into inflamed joint fluid, saliva, bile, urine, sebum, cerumen, feces, tendons, skin and soft tissue, and testes; crosses blood-brain barrier poorly; only negligible amounts reach CSF

Metabolism

Partially hepatic via CYP3A4 to inactive metabolites

Excretion

Feces (57%); urine (13% [2% to 4% unchanged]).

Time to Peak

Serum: 1-2 hours

Half-Life Elimination

Biphasic: Initial: 2 hours; Terminal: 8 hours

Protein Binding

~99% (mainly albumin)

Use: Labeled Indications

Fungal infections (systemic):

US labeling: Treatment of susceptible systemic fungal infections, including blastomycosis, histoplasmosis, paracoccidioidomycosis, coccidioidomycosis, and chromomycosis in patients who have failed or who are intolerant to other antifungal therapies

Limitations of use: Ketoconazole should only be used when other effective antifungal therapy is not available or tolerated and the potential benefits outweigh the potential risks. Ketoconazole tablets are not indicated for the treatment of onychomycosis, cutaneous dermatophyte infections, or Candida infections.

Canadian labeling: Treatment of serious or life-threatening systemic fungal infections (eg, systemic candidiasis, chronic mucocutaneous candidiasis, coccidioidomycosis, paracoccidioidomycosis, histoplasmosis, and chromomycosis) where alternate therapy is inappropriate or ineffective; may be considered for severe dermatophytoses unresponsive to other therapy

Off Label Uses

Cushing syndrome

Data from a retrospective multicenter study and other noncontrolled studies and case reports support the use of ketoconazole in the management of patients with Cushing syndrome [Castinetti 2014], [Miller 1993], [Moncet 2007]. However, the potential for ketoconazole-related hepatotoxicity should be considered; close monitoring of liver enzymes is advised.

Based on the Endocrine Society clinical practice guideline for treatment of Cushing syndrome, ketoconazole is an effective and recommended agent for the treatment of Cushing syndrome. Treatment with a steroidogenesis inhibitor (eg, ketoconazole) is recommended as second-line therapy after transsphenoidal selective adenomectomy (with or without radiation therapy or radiosurgery), as primary treatment of occult or metastatic ectopic adrenocorticotropic hormone (ACTH) secretion, or as adjunctive treatment to decrease cortisol levels in adrenocortical carcinoma [ES [Nieman 2015]]. Access Full-Off Label Monograph

Prostate cancer, advanced

Data from two prospective, randomized trials in patients with prostate cancer and the antiandrogen withdrawal (AAWD) phenomenon support the use of ketoconazole (in combination with oral hydrocortisone) in the treatment of this condition [Ryan 2007], [Small 2003].

Contraindications

Hypersensitivity to ketoconazole or any component of the formulation; acute or chronic liver disease; coadministration with alprazolam, cisapride, colchicine, disopyramide, dofetilide, dronedarone, eplerenone, ergot alkaloids (eg, dihydroergotamine, ergometrine, ergotamine, methylergometrine), felodipine, HMG-CoA reductase inhibitors (eg, lovastatin, simvastatin), irinotecan, lurasidone, methadone, oral midazolam, nisoldipine, pimozide, quinidine, ranolazine, tolvaptan, triazolam

Canadian labeling: Additional contraindications (not in US labeling): Women of childbearing potential unless effective forms of contraception are used; coadministration with astemizole or terfenadine

Dosing: Adult

Fungal infections (systemic): Oral: 200 mg once daily; may increase to 400 mg once daily if response is insufficient. Continue until active fungal infection is resolved; some infections may require a treatment duration of up to 6 months.

Prostate cancer, advanced (off-label use): Oral: 400 mg 3 times daily (in combination with oral hydrocortisone) until disease progression (Ryan 2007; Small 2004)

Cushing syndrome (off-label use): Oral: Initial: 400 to 600 mg daily in 2 or 3 divided doses; may increase dose by 200 mg daily every 7 to 28 days up to a maximum of 1,200 mg daily in 2 or 3 divided doses; dosage range: 200 to 1,200 mg daily; mean effective dose in most studies: 600 to 800 mg daily in 2 divided doses (Castinetti 2014; ES [Nieman 2015]; Miller 1993)

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Fungal infections (systemic): Children ≥2 years and Adolescents: Oral: 3.3 to 6.6 mg/kg/day once daily; maximum daily dose: 400 mg/day; duration of therapy variable based on pathogen, patient, and disease-specific factors. Note: Usual adult dose: 200 mg/day; systemic ketoconazole should only be used when other effective antifungal therapy is not available or tolerated due to potential for serious adverse reactions.

Peripheral precocious puberty (gonadotropin-independent): Very limited data available, optimal dose not defined: Children ≥2 years and Adolescents: Oral: 10 to 20 mg/kg/day in 3 divided doses (Schoelwer 2016; Kliegman 2020). Reported doses in patients with familial male-limited precocious puberty or McCune-Albright syndrome vary widely; however, all describe response with decreased testosterone levels and cessation of puberty; some authors report flat doses of 400 to 600 mg/day divided 2 to 3 times daily (Holland 1987; Messina 2008; Syed 1999); others describe weight-based doses as high as 30 mg/kg/day in 3 divided doses (Almeida 2008; Soriano-Guillén 2005).

Cushing syndrome, second-line therapy: Very limited data available: Children ≥12 years and Adolescents: Oral: Initial: 400 to 600 mg/day in 2 or 3 divided doses; doses can be increased by 200 mg/day every 7 to 28 days based on patient response (urinary or plasma cortisol) and tolerability to 800 to 1,200 mg/day in 2 or 3 divided doses (Young 2018; European Medicines Agency 2020). In one compassionate use trial of adult and pediatric patients with Cushing syndrome (n=108; mean age: 51.3 years; range: 11 to 86 years), median final dose of ketoconazole was 600 mg/day (range: 200 to 1,200 mg/day) in divided doses (Young 2018).

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Extemporaneously Prepared

20 mg/mL Oral Suspension

A 20 mg/mL oral suspension may be made with tablets and one of three different vehicles (a 1:1 mixture of Ora-Sweet® and Ora-Plus®, a 1:1 mixture of Ora-Sweet® SF and Ora-Plus®, or a 1:4 mixture of cherry syrup and Simple Syrup, NF). Crush twelve 200 mg tablets in a mortar and reduce to a fine powder. Add 20 mL of chosen vehicle and mix to a uniform paste; mix while adding the vehicle in incremental proportions to almost 120 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 120 mL. Label "shake well" and "refrigerate". Stable for 60 days.

Nahata MC, Pai VB, and Hipple TF, Pediatric Drug Formulations, 5th ed, Cincinnati, OH: Harvey Whitney Books Co, 2004.

Administration

Administer oral tablets 2 hours prior to antacids to prevent decreased absorption due to the high pH of gastric contents. Patients with achlorhydria should administer with acidic liquid (eg, soda pop).

Storage

Store at 20°C to 25°C (68°F to 77°F).

Drug Interactions

Abemaciclib: Ketoconazole (Systemic) may increase the serum concentration of Abemaciclib. Avoid combination

Acalabrutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Acalabrutinib. Avoid combination

Ado-Trastuzumab Emtansine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Ado-Trastuzumab Emtansine. Specifically, strong CYP3A4 inhibitors may increase concentrations of the cytotoxic DM1 component. Management: Avoid concomitant use of ado-trastuzumab emtansine and strong CYP3A4 inhibitors when possible. Consider alternatives that do not inhibit CYP3A4 or consider administering after CYP3A4 inhibitor discontinuation. Monitor for toxicities if combined. Consider therapy modification

Afatinib: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Afatinib. Management: If combined, administer the P-gp inhibitor simultaneously with, or after, the dose of afatinib. Monitor closely for signs and symptoms of afatinib toxicity and if the combination is not tolerated, reduce the afatinib dose by 10 mg. Consider therapy modification

Alcohol (Ethyl): Ketoconazole (Systemic) may enhance the adverse/toxic effect of Alcohol (Ethyl). Management: Advise patients to avoid alcohol ingestion while taking ketoconazole. Consider therapy modification

Alfentanil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Alfentanil. Management: If use of alfentanil and strong CYP3A4 inhibitors is necessary, consider dosage reduction of alfentanil until stable drug effects are achieved. Frequently monitor patients for respiratory depression and sedation when these agents are combined. Consider therapy modification

Alfuzosin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Alfuzosin. Avoid combination

Aliskiren: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Aliskiren. Monitor therapy

Alitretinoin (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Alitretinoin (Systemic). Management: Consider reducing the alitretinoin dose to 10 mg when used together with strong CYP3A4 inhibitors. Monitor for increased alitretinoin effects/toxicities if combined with a strong CYP3A4 inhibitor. Consider therapy modification

Almotriptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Almotriptan. Management: Limit initial almotriptan dose to 6.25 mg and maximum dose to 12.5 mg in any 24-period when used with a strong CYP3A4 inhibitor. Avoid concurrent use in patients with impaired hepatic or renal function. Consider therapy modification

Alosetron: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Alosetron. Monitor therapy

ALPRAZolam: Ketoconazole (Systemic) may increase the serum concentration of ALPRAZolam. Avoid combination

Amphotericin B: Antifungal Agents (Azole Derivatives, Systemic) may diminish the therapeutic effect of Amphotericin B. Monitor therapy

Antacids: May decrease the serum concentration of Ketoconazole (Systemic). Management: Administer oral ketoconazole at least 2 hours prior to use of any antacid product. Monitor patients closely for signs of inadequate clinical response to ketoconazole. Consider therapy modification

Antihepaciviral Combination Products: May increase the serum concentration of Ketoconazole (Systemic). Ketoconazole (Systemic) may increase the serum concentration of Antihepaciviral Combination Products. Specifically, ketoconazole may increase serum concentrations of paritaprevir. Management: Limit the dose of ketoconazole to 200 mg per day in patients taking antihepaciviral combination products. Additionally, monitor for increased ketoconazole effects/toxicities and for increased paritaprevir effects/toxicities. Consider therapy modification

Apixaban: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Apixaban. Management: US labeling recommends a 50% apixaban dose reduction in patients who would otherwise receive 5 or 10 mg twice daily, and avoiding in patients who would otherwise receive 2.5 mg twice daily. Canadian labeling lists any combined use as contraindicated. Consider therapy modification

Aprepitant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Aprepitant. Avoid combination

ARIPiprazole: CYP3A4 Inhibitors (Strong) may increase the serum concentration of ARIPiprazole. Management: Aripiprazole dose reductions are required for indications other than major depressive disorder. Dose reductions vary based on formulation, CYP2D6 genotype, and use of CYP2D6 inhibitors. See full interaction monograph for details. Consider therapy modification

ARIPiprazole Lauroxil: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of ARIPiprazole Lauroxil. Management: Decrease aripiprazole lauroxil dose to next lower strength if used with strong CYP3A4 inhibitors for over 14 days. No dose adjustment needed if using the lowest dose (441 mg). Max dose is 441 mg in CYP2D6 PMs or if also taking strong CYP2D6 inhibitors. Consider therapy modification

Astemizole: Ketoconazole (Systemic) may enhance the QTc-prolonging effect of Astemizole. Ketoconazole (Systemic) may increase the serum concentration of Astemizole. Avoid combination

Asunaprevir: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Asunaprevir. Avoid combination

AtorvaSTATin: May enhance the adverse/toxic effect of Ketoconazole (Systemic). Specifically, there is a theoretical potential for additive effects on reducing endogenous steroid concentrations. Ketoconazole (Systemic) may increase the serum concentration of AtorvaSTATin. Management: Administer ketoconazole with atorvastatin cautiously, and monitor for toxic effects of atorvastatin (e.g., myalgia, rhabdomyolysis, liver function test abnormalities). Consider use of fluva-, rosuva-, pitava-, or pravastatin when possible. Consider therapy modification

Avanafil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Avanafil. Avoid combination

Avapritinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Avapritinib. Avoid combination

Axitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Axitinib. Management: Avoid concurrent use of axitinib with any strong CYP3A inhibitor whenever possible. If a strong CYP3A inhibitor must be used with axitinib, a 50% axitinib dose reduction is recommended. Consider therapy modification

Barnidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Barnidipine. Avoid combination

Bedaquiline: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bedaquiline. Management: Limit duration of concurrent use of bedaquiline with CYP3A4 inhibitors to no more than 14 days, unless the benefit of continued use outweighs the possible risks. Monitor for toxic effects of bedaquiline. Consider therapy modification

Benperidol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Benperidol. Monitor therapy

Benzhydrocodone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Benzhydrocodone. Specifically, the concentration of hydrocodone may be increased. Monitor therapy

Betamethasone (Ophthalmic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Betamethasone (Ophthalmic). Monitor therapy

Betamethasone (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Betamethasone (Systemic). Monitor therapy

Betrixaban: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Betrixaban. Management: Decrease adult betrixaban dose to an initial single dose of 80 mg followed by 40 mg once daily if combined with a P-gp inhibitor. Avoid concomitant use of betrixaban and P-gp inhibitors in patients with severe renal impairment (CrCL less than 30 mL/min). Consider therapy modification

Bictegravir: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bictegravir. Monitor therapy

Bilastine: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Bilastine. Avoid combination

Blonanserin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Blonanserin. Avoid combination

Bortezomib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bortezomib. Monitor therapy

Bosentan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bosentan. Monitor therapy

Bosutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bosutinib. Avoid combination

Brentuximab Vedotin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Brentuximab Vedotin. Specifically, concentrations of the active monomethyl auristatin E (MMAE) component may be increased. Monitor therapy

Brexpiprazole: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Brexpiprazole. Management: Reduce brexpiprazole dose 50% with strong CYP3A4 inhibitors; reduce to 25% of usual if used with both a strong CYP3A4 inhibitor and a CYP2D6 inhibitor in patients not being treated for MDD, or strong CYP3A4 inhibitor used in a CYP2D6 poor metabolizer. Consider therapy modification

Brigatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Brigatinib. Management: Avoid concurrent use of brigatinib with strong CYP3A4 inhibitors when possible. If combination cannot be avoided, reduce the brigatinib dose by approximately 50%, rounding to the nearest tablet strength (ie, from 180 mg to 90 mg, or from 90 mg to 60 mg). Consider therapy modification

Bromocriptine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bromocriptine. Management: Consider alternatives to the use of bromocriptine with strong CYP3A4 inhibitors. If combined, monitor closely for increased bromocriptine toxicities and consider bromocriptine dose reductions. Consider therapy modification

Bromperidol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Bromperidol. Monitor therapy

Budesonide (Nasal): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Budesonide (Nasal). Monitor therapy

Budesonide (Oral Inhalation): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Budesonide (Oral Inhalation). Monitor therapy

Budesonide (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Budesonide (Systemic). Management: Avoid the concomitant use of CYP3A4 inhibitors and oral budesonide. If patients receive both budesonide and a strong CYP3A4 inhibitor, they should be closely monitored for signs and symptoms of corticosteroid excess. Consider therapy modification

Budesonide (Topical): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Budesonide (Topical). Avoid combination

Buprenorphine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Buprenorphine. Monitor therapy

BusPIRone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of BusPIRone. Management: Limit the buspirone dose to 2.5 mg daily and monitor patients for increased buspirone effects/toxicities if combined with strong CYP3A4 inhibitors. Consider therapy modification

Busulfan: Antifungal Agents (Azole Derivatives, Systemic) may increase the serum concentration of Busulfan. Isavuconazonium considerations are addressed in separate monographs. Monitor therapy

Cabazitaxel: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cabazitaxel. Management: Concurrent use of cabazitaxel with strong inhibitors of CYP3A4 should be avoided when possible. If such a combination must be used, consider a 25% reduction in the cabazitaxel dose. Consider therapy modification

Cabozantinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cabozantinib. Management: Avoid use of a strong CYP3A4 inhibitor with cabozantinib if possible. If combined, decrease cabozantinib capsules (Cometriq) by 40 mg from previous dose or decrease cabozantinib tablets (Cabometyx) by 20 mg from previous dose. Consider therapy modification

Calcifediol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Calcifediol. Monitor therapy

Calcium Channel Blockers: Antifungal Agents (Azole Derivatives, Systemic) may enhance the adverse/toxic effect of Calcium Channel Blockers. Specifically, itraconazole may enhance the negative inotropic effects of verapamil or diltiazem. Antifungal Agents (Azole Derivatives, Systemic) may decrease the metabolism of Calcium Channel Blockers. Fluconazole and isavuconazonium likely exert weaker effects than other azoles and are addressed in separate monographs. Management: Concurrent use of felodipine or nisoldipine with itraconazole is specifically contraindicated. Frequent monitoring is warranted with any such combination; calcium channel blocker dose reductions may be required. Consider therapy modification

Cannabidiol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cannabidiol. Monitor therapy

Cannabis: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cannabis. More specifically, tetrahydrocannabinol and cannabidiol serum concentrations may be increased. Monitor therapy

Capmatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Capmatinib. Monitor therapy

Carbocisteine: Ketoconazole (Systemic) may enhance the adverse/toxic effect of Carbocisteine. Specifically, ketoconazole may enhance adverse effects of alcohol that is present in liquid formulations of carbocisteine-containing products. Management: Advise patients to avoid alcohol ingestion while taking ketoconazole. Liquid formulations of carbcisteine-containing products contain alcohol, which may interact with ketoconazole in some patients. Consider therapy modification

Cariprazine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cariprazine. Management: Decrease cariprazine dose 50% (4.5 mg to 1.5 mg or 3 mg; 1.5 mg to 1.5 mg every other day) if starting a strong CYP3A4 inhibitor. If on a strong CYP3A4 inhibitor, start cariprazine at 1.5 mg day 1, 0 mg day 2, then 1.5 mg daily. May increase to 3 mg daily Consider therapy modification

Celiprolol: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Celiprolol. Monitor therapy

Ceritinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ceritinib. Management: If such combinations cannot be avoided, the ceritinib dose should be reduced by approximately one-third (to the nearest 150 mg). Resume the prior ceritinib dose after cessation of the strong CYP3A4 inhibitor. Consider therapy modification

Choline C 11: Antiandrogens may diminish the therapeutic effect of Choline C 11. Monitor therapy

Ciclesonide (Oral Inhalation): CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Ciclesonide (Oral Inhalation). Monitor therapy

Cilostazol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cilostazol. Management: Consider reducing the cilostazol dose to 50 mg twice daily in adult patients who are also receiving strong inhibitors of CYP3A4. Consider therapy modification

Cinacalcet: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cinacalcet. Monitor therapy

Cisapride: Ketoconazole (Systemic) may increase the serum concentration of Cisapride. Avoid combination

CloBAZam: CYP2C19 Inhibitors (Weak) may increase serum concentrations of the active metabolite(s) of CloBAZam. CYP2C19 Inhibitors (Weak) may increase the serum concentration of CloBAZam. Monitor therapy

CloZAPine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of CloZAPine. Monitor therapy

Cobicistat: Ketoconazole (Systemic) may increase the serum concentration of Cobicistat. Cobicistat may increase the serum concentration of Ketoconazole (Systemic). Management: Limit ketoconazole to a maximum adult dose of 200 mg/day in patients being treated with the elvitegravir/cobicistat/emtricitabine/tenofovir combination product. Dosing recommendations for other cobicistat-containing products are not available. Consider therapy modification

Cobimetinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cobimetinib. Avoid combination

Codeine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Codeine. Monitor therapy

Colchicine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Colchicine. Management: Colchicine is contraindicated in patients with impaired renal or hepatic function who are also receiving a strong CYP3A4 inhibitor. In those with normal renal and hepatic function, reduce colchicine dose as directed. See interaction monograph for details. Consider therapy modification

Colchicine: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Colchicine. Colchicine distribution into certain tissues (e.g., brain) may also be increased. Management: Colchicine is contraindicated in patients with impaired renal or hepatic function who are also receiving a P-gp inhibitor. In those with normal renal and hepatic function, reduce colchicine dose as directed. See interaction monograph for details. Consider therapy modification

Conivaptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Conivaptan. Avoid combination

Copanlisib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Copanlisib. Management: If concomitant use of copanlisib and strong CYP3A4 inhibitors cannot be avoided, reduce the copanlisib dose to 45 mg. Monitor patients for increased copanlisib effects/toxicities. Consider therapy modification

Cortisone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Cortisone. Monitor therapy

Crizotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Crizotinib. Management: Avoid concomitant use of crizotinib and strong CYP3A4 inhibitors whenever possible. If combined use cannot be avoided, decrease the crizotinib dose to 250 mg daily. Consider therapy modification

CycloSPORINE (Systemic): Antifungal Agents (Azole Derivatives, Systemic) may decrease the metabolism of CycloSPORINE (Systemic). Fluconazole and isavuconazonium considerations are addressed in separate monographs. Management: Consider reducing cyclosporine doses by 50% to 80% during coadministration with ketoconazole, 50% with voriconazole or itraconazole, and 25% with posaconazole. Cyclosporine dose reductions may be required with other azoles. Consider therapy modification

CycloSPORINE (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of CycloSPORINE (Systemic). Management: Monitor cyclosporine serum concentrations and clinical cyclosporine closely with concurrent use of any strong CYP3A4 inhibitor. Cyclosporine dose reductions and/or prolongation of the dosing interval will likely be required. Consider therapy modification

CYP3A4 Inducers (Moderate): May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy

CYP3A4 Inducers (Strong): May decrease the serum concentration of Ketoconazole (Systemic). Management: The use of ketoconazole concurrently with or within 2 weeks of a strong CYP3A4 inducer is not recommended. If such a combination cannot be avoided, monitor patients closely for evidence of diminished clinical response to ketoconazole. Consider therapy modification

CYP3A4 Substrates (High risk with Inhibitors): CYP3A4 Inhibitors (Strong) may decrease the metabolism of CYP3A4 Substrates (High risk with Inhibitors). Management: Consider avoiding this combination. Some combinations are specifically contraindicated by manufacturers; others may have recommended dose adjustments. If combined, monitor for increased substrate effects. Consider therapy modification

Dabigatran Etexilate: Ketoconazole (Systemic) may increase the serum concentration of Dabigatran Etexilate. Management: Dose reductions and/or avoidance of this combination may be necessary. Specific recommendations vary by renal function and indication for dabigatran. Refer to full interaction monograph for details. Consider therapy modification

Dabrafenib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dabrafenib. Avoid combination

Daclatasvir: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Daclatasvir. Management: Decrease the daclatasvir dose to 30 mg once daily if combined with a strong CYP3A4 inhibitor. No dose adjustment is needed when daclatasvir is used with darunavir/cobicistat. Consider therapy modification

Dapoxetine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dapoxetine. Avoid combination

Darifenacin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Darifenacin. Management: Limit the darifenacin dose to no more than 7.5 mg daily if combined with strong CYP3A4 inhibitors. Monitor patients for increased darifenacin toxicities (eg, dry mouth, constipation, headache, CNS effects) when these agents are combined. Consider therapy modification

Darolutamide: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Darolutamide. Monitor therapy

Darunavir: May increase the serum concentration of Ketoconazole (Systemic). Ketoconazole (Systemic) may increase the serum concentration of Darunavir. Management: Limit the adult maximum ketoconazole dose to 200 mg/day in patients receiving darunavir/ritonavir. Consider therapy modification

Dasatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dasatinib. Management: This combination should be avoided if possible. If combined, decrease dasatinib dose from 140 mg to 40 mg, 100 mg to 20 mg, or 70 mg to 20 mg. For patients taking 60 mg or 40 mg daily, stop dasatinib until the CYP3A4 inhibitor is discontinued. Consider therapy modification

Deferasirox: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy

Deflazacort: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Deflazacort. Management: Administer one third of the recommended deflazacort dose when used together with a strong or moderate CYP3A4 inhibitor. Consider therapy modification

Delamanid: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Delamanid. Management: Increase ECG monitoring frequency if delamanid is combined with strong CYP3A4 inhibitors due to the risk for QTc interval prolongation. Continue frequent ECG assessments throughout full delamanid treatment period. Consider therapy modification

DexAMETHasone (Ophthalmic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of DexAMETHasone (Ophthalmic). Monitor therapy

Dichlorphenamide: Antifungal Agents (Azole Derivatives, Systemic) may enhance the hypokalemic effect of Dichlorphenamide. Monitor therapy

Didanosine: May decrease the serum concentration of Ketoconazole (Systemic). Management: Administer oral ketoconazole at least 2 hours prior to buffered didanosine. This interaction is not expected with enteric-coated didanosine capsules since they do not contain buffering agents. Consider therapy modification

Dienogest: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dienogest. Monitor therapy

Digitoxin: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Digitoxin. Monitor therapy

Dihydroergotamine: Ketoconazole (Systemic) may increase the serum concentration of Dihydroergotamine. Avoid combination

Disopyramide: Ketoconazole (Systemic) may increase the serum concentration of Disopyramide. Avoid combination

DOCEtaxel: CYP3A4 Inhibitors (Strong) may increase the serum concentration of DOCEtaxel. Management: Avoid the concomitant use of docetaxel and strong CYP3A4 inhibitors when possible. If combined use is unavoidable, consider a 50% docetaxel dose reduction and monitor for increased docetaxel toxicities. Consider therapy modification

Dofetilide: Ketoconazole (Systemic) may increase the serum concentration of Dofetilide. Avoid combination

Domperidone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Domperidone. Avoid combination

Doxercalciferol: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Doxercalciferol. Monitor therapy

DOXOrubicin (Conventional): P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of DOXOrubicin (Conventional). Avoid combination

Dronabinol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dronabinol. Monitor therapy

Dronedarone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dronedarone. Management: Concurrent use of strong CYP3A4 inhibitors with dronedarone is contraindicated according to dronedarone prescribing information. Avoid combination

Drospirenone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Drospirenone. Management: Drospirenone use is contraindicated specifically when the strong CYP3A4 inhibitors atazanavir and cobicistat are administered concurrently. Caution should be used when drospirenone is coadministered with other strong CYP3A4 inhibitors. Consider therapy modification

Dutasteride: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Dutasteride. Monitor therapy

Duvelisib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Duvelisib. Management: Reduce the dose of duvelisib to 15 mg twice a day when used together with a strong CYP3A4 inhibitor. Monitor closely for evidence of altered response to treatment. Consider therapy modification

Edoxaban: Ketoconazole (Systemic) may increase the serum concentration of Edoxaban. Management: In patients treated for DVT/PE, reduce the edoxaban dose to 30 mg daily when combined with oral ketoconazole. No dose adjustment is recommended for patients treated for atrial fibrillation. Monitor for increased edoxaban toxicities (ie, bleeding). Consider therapy modification

Efavirenz: May decrease the serum concentration of Ketoconazole (Systemic). Avoid combination

Elagolix: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Elagolix. Management: Use of the elagolix 200 mg twice daily dose with a strong CYP3A4 inhibitor for longer than 1 month is not recommended. Limit combined use of the elagolix 150 mg once daily dose with a strong CYP3A4 inhibitor to a maximum of 6 months. Consider therapy modification

Elagolix, Estradiol, and Norethindrone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Elagolix, Estradiol, and Norethindrone. Avoid combination

Elbasvir: Ketoconazole (Systemic) may increase the serum concentration of Elbasvir. Avoid combination

Eletriptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Eletriptan. Avoid combination

Elexacaftor, Tezacaftor, and Ivacaftor: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Elexacaftor, Tezacaftor, and Ivacaftor. Management: When combined with strong CYP3A4 inhibitors, administer two elexacaftor/tezacaftor/ivacaftor tablets (100 mg/50 mg/75 mg) in the morning, twice a week, approximately 3 to 4 days apart. No evening doses of ivacaftor (150 mg) alone should be administered. Consider therapy modification

Eliglustat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Eliglustat. Management: Reduce eliglustat dose to 84 mg daily in CYP2D6 EMs when used with strong CYP3A4 inhibitors. Use of strong CYP3A4 inhibitors is contraindicated in CYP2D6 IMs, PMs, or in CYP2D6 EMs who are also taking strong or moderate CYP2D6 inhibitors. Consider therapy modification

Elvitegravir: Ketoconazole (Systemic) may increase the serum concentration of Elvitegravir. Management: Limit ketoconazole to a maximum dose of 200 mg/day in patients who are being treated with an elvitegravir-containing product. Monitor for ketoconazole or elvitegravir toxicity in patients receiving this combination. Consider therapy modification

Emedastine (Systemic): Ketoconazole (Systemic) may increase the serum concentration of Emedastine (Systemic). Monitor therapy

Encorafenib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Encorafenib. Management: Avoid use of encorafenib and strong CYP3A4 inhibitors when possible. If combined, decrease encorafenib from 450 mg to 150 mg; or from 300 mg, 225 mg, or 150 mg to 75 mg. Once the CYP3A4 inhibitor is discontinued for 3 to 5 half-lives, resume prior dose. Consider therapy modification

Enfortumab Vedotin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Enfortumab Vedotin. Specifically, concentrations of the active monomethyl auristatin E (MMAE) component may be increased. Monitor therapy

Entrectinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Entrectinib. Management: Avoid strong CYP3A4 inhibitors during treatment with entrectinib when possible. If combined in adults and those 12 yrs of age or older with a BSA of at least 1.5 square meters, reduce dose to 100 mg/day. Avoid if BSA is less than 1.5 square meters. Consider therapy modification

Enzalutamide: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Concurrent use of enzalutamide with CYP3A4 substrates that have a narrow therapeutic index should be avoided. Use of enzalutamide and any other CYP3A4 substrate should be performed with caution and close monitoring. Consider therapy modification

Eplerenone: Ketoconazole (Systemic) may increase the serum concentration of Eplerenone. Avoid combination

Erdafitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Erdafitinib. Management: Avoid concomitant use of erdafitinib and strong CYP3A4 inhibitors when possible. If combined, monitor closely for erdafitinib adverse reactions and consider dose modifications accordingly. Consider therapy modification

Ergoloid Mesylates: Ketoconazole (Systemic) may increase the serum concentration of Ergoloid Mesylates. Avoid combination

Ergonovine: Ketoconazole (Systemic) may increase the serum concentration of Ergonovine. Avoid combination

Ergotamine: Ketoconazole (Systemic) may increase the serum concentration of Ergotamine. Avoid combination

Erlotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Erlotinib. Management: Avoid use of this combination when possible. When the combination must be used, monitor the patient closely for the development of severe adverse reactions, and if such severe reactions occur, reduce the erlotinib dose (in 50 mg decrements). Consider therapy modification

Estazolam: Ketoconazole (Systemic) may increase the serum concentration of Estazolam. Avoid combination

Estrogen Derivatives: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Estrogen Derivatives. Monitor therapy

Eszopiclone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Eszopiclone. Management: Limit the eszopiclone dose to 2 mg daily when combined with strong CYP3A4 inhibitors and monitor for increased eszopiclone effects and toxicities (eg, somnolence, drowsiness, CNS depression). Consider therapy modification

Etizolam: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Etizolam. Management: Consider use of lower etizolam doses when using this combination; specific recommendations concerning dose adjustment are not available. Monitor clinical response to the combination closely. Consider therapy modification

Etoposide: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Etoposide. Monitor therapy

Etoposide Phosphate: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Etoposide Phosphate. Monitor therapy

Etravirine: Antifungal Agents (Azole Derivatives, Systemic) may increase the serum concentration of Etravirine. Etravirine may decrease the serum concentration of Antifungal Agents (Azole Derivatives, Systemic). This would be anticipated with itraconazole or ketoconazole. Monitor therapy

Everolimus: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Everolimus. Avoid combination

Evogliptin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Evogliptin. Monitor therapy

Fedratinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fedratinib. Management: Consider alternatives when possible. If used together, decrease fedratinib dose to 200 mg/day. After the inhibitor is stopped, increase fedratinib to 300 mg/day for the first 2 weeks and then to 400 mg/day as tolerated. Consider therapy modification

Felodipine: Ketoconazole (Systemic) may increase the serum concentration of Felodipine. Avoid combination

FentaNYL: CYP3A4 Inhibitors (Strong) may increase the serum concentration of FentaNYL. Management: Consider fentanyl dose reductions when combined with a strong CYP3A4 inhibitor. Monitor for respiratory depression and sedation. Upon discontinuation of a CYP3A4 inhibitor, consider a fentanyl dose increase; monitor for signs and symptoms of withdrawal. Consider therapy modification

Fesoterodine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Fesoterodine. Management: Limit fesoterodine doses to 4 mg daily in patients who are also receiving strong CYP3A4 inhibitors. Consider therapy modification

Fimasartan: Ketoconazole (Systemic) may increase the serum concentration of Fimasartan. Monitor therapy

Fingolimod: Ketoconazole (Systemic) may increase serum concentrations of the active metabolite(s) of Fingolimod. Ketoconazole (Systemic) may increase the serum concentration of Fingolimod. Monitor therapy

Flibanserin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Flibanserin. Management: Use of flibanserin with strong CYP3A4 inhibitors is contraindicated. If starting flibanserin, start 2 weeks after the last dose of the CYP3A4 inhibitor. If starting a CYP3A4 inhibitor, start 2 days after the last dose of flibanserin. Avoid combination

Fluticasone (Nasal): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fluticasone (Nasal). Avoid combination

Fluticasone (Oral Inhalation): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fluticasone (Oral Inhalation). Consider therapy modification

Fosamprenavir: Ketoconazole (Systemic) may increase serum concentrations of the active metabolite(s) of Fosamprenavir. Specifically, amprenavir concentrations may be increased. Fosamprenavir may increase the serum concentration of Ketoconazole (Systemic). Management: Limit the adult maximum ketoconazole dose to 200 mg/day with fosamprenavir/ritonavir. In patients receiving fosamprenavir without ritonavir, patients receiving greater than 400 mg/day ketoconazole may also require dose reduction. Consider therapy modification

Fosaprepitant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Fosaprepitant. Avoid combination

Fostamatinib: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Fostamatinib. Monitor therapy

Galantamine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Galantamine. Monitor therapy

Gefitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Gefitinib. Monitor therapy

Gilteritinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Gilteritinib. Management: Consider alternatives to the use of a strong CYP3A4 inhibitor with gilteritinib. If the combination cannot be avoided, monitor more closely for evidence of gilteritinib toxicities. Consider therapy modification

Glasdegib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Glasdegib. Management: Consider alternatives to this combination when possible. If the combination must be used, monitor closely for evidence of QT interval prolongation and other adverse reactions to glasdegib. Consider therapy modification

Glecaprevir and Pibrentasvir: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Glecaprevir and Pibrentasvir. Monitor therapy

Grazoprevir: Ketoconazole (Systemic) may increase the serum concentration of Grazoprevir. Avoid combination

GuanFACINE: CYP3A4 Inhibitors (Strong) may increase the serum concentration of GuanFACINE. Management: Reduce the extended-release guanfacine dose 50% when combined with a strong CYP3A4 inhibitor. Monitor for increased guanfacine toxicities when these agents are combined. Consider therapy modification

Halofantrine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Halofantrine. Management: The combination of halofantrine with a strong CYP3A4 inhibitor should be avoided whenever possible due to the risk for QTc interval prolongation. Avoid combination

Histamine H2 Receptor Antagonists: May decrease the serum concentration of Ketoconazole (Systemic). Management: Administer oral ketoconazole at least 2 hours prior to use of any H2-receptor antagonist. Monitor patients closely for signs of inadequate clinical response to ketoconazole. Consider therapy modification

HYDROcodone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of HYDROcodone. Monitor therapy

Hydrocortisone (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Hydrocortisone (Systemic). Monitor therapy

Hyoscyamine: May decrease the serum concentration of Ketoconazole (Systemic). Management: Take hyoscyamine at least 2 hours after ingestion of ketoconazole. Monitor for decreased therapeutic effects of ketoconazole if used together with hyoscyamine. Consider therapy modification

Ibrutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ibrutinib. Management: Avoid concomitant use of ibrutinib and strong CYP3A4 inhibitors. If a strong CYP3A4 inhibitor must be used short-term (eg, anti-infectives for 7 days or less), interrupt ibrutinib therapy until the strong CYP3A4 inhibitor is discontinued. Avoid combination

Idelalisib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Idelalisib. Monitor therapy

Ifosfamide: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Ifosfamide. Monitor therapy

Iloperidone: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Iloperidone. Specifically, concentrations of the metabolites P88 and P95 may be increased. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Iloperidone. Management: Reduce iloperidone dose by half when administered with a strong CYP3A4 inhibitor. Consider therapy modification

Imatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Imatinib. Monitor therapy

Imidafenacin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Imidafenacin. Monitor therapy

Indinavir: Ketoconazole (Systemic) may increase the serum concentration of Indinavir. Indinavir may increase the serum concentration of Ketoconazole (Systemic). Management: Reduce the indinavir dose to 600 mg every 8 hours when given with ketoconazole. Monitor for increased systemic effects (including adverse/toxic effects) of ketoconazole. Consider therapy modification

Indium 111 Capromab Pendetide: Antiandrogens may diminish the diagnostic effect of Indium 111 Capromab Pendetide. Avoid combination

Irinotecan Products: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Irinotecan Products. Specifically, serum concentrations of SN-38 may be increased. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Irinotecan Products. Avoid combination

Isavuconazonium Sulfate: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Isavuconazonium Sulfate. Specifically, CYP3A4 Inhibitors (Strong) may increase isavuconazole serum concentrations. Management: Combined use is considered contraindicated per US labeling. Lopinavir/ritonavir (and possibly other uses of ritonavir doses less than 400 mg every 12 hours) is treated as a possible exception to this contraindication despite strongly inhibiting CYP3A4. Avoid combination

Isoniazid: May decrease the serum concentration of Ketoconazole (Systemic). Monitor therapy

Istradefylline: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Istradefylline. Management: Limit the maximum istradefylline dose to 20 mg daily when combined with strong CYP3A4 inhibitors and monitor for increased istradefylline effects/toxicities. Consider therapy modification

Ivabradine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ivabradine. Avoid combination

Ivacaftor: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ivacaftor. Management: Ivacaftor dose reductions are required; consult full drug interaction monograph content for age- and weight-specific recommendations. Consider therapy modification

Ivosidenib: Ketoconazole (Systemic) may increase the serum concentration of Ivosidenib. Ivosidenib may decrease the serum concentration of Ketoconazole (Systemic). Avoid combination

Ixabepilone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ixabepilone. Management: Avoid use of ixabepilone and strong CYP3A4 inhibitors when possible. If combined, reduce the ixabepilone dose to 20 mg/m2. The previous ixabepilone dose can be resumed 1 week after discontinuation of the strong CYP3A4 inhibitor. Consider therapy modification

Lapatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lapatinib. Management: Avoid use of lapatinib and strong CYP3A4 inhibitors when possible. If combined, reduce lapatinib dose to 500 mg daily. The previous lapatinib dose can be resumed 1 week after discontinuation of the strong CYP3A4 inhibitor. Consider therapy modification

Larotrectinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Larotrectinib. Management: Avoid use of strong CYP3A4 inhibitors with larotrectinib. If this combination cannot be avoided, reduce the larotrectinib dose by 50%. Increase to previous dose after stopping the inhibitor after a period of 3 to 5 times the inhibitor's half-life. Consider therapy modification

Lefamulin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lefamulin. Management: Avoid concomitant use of lefamulin tablets and strong inhibitors of CYP3A4. Avoid combination

Lemborexant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lemborexant. Avoid combination

Lercanidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lercanidipine. Avoid combination

Levobupivacaine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Levobupivacaine. Monitor therapy

Levomilnacipran: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Levomilnacipran. Management: Do not exceed a maximum adult levomilnacipran dose of 80 mg/day in patients also receiving strong CYP3A4 inhibitors. Consider therapy modification

Lomitapide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lomitapide. Avoid combination

Lopinavir: Ketoconazole (Systemic) may increase the serum concentration of Lopinavir. Lopinavir may increase the serum concentration of Ketoconazole (Systemic). Management: Limit the adult maximum ketoconazole dose to 200 mg/day in patients receiving lopinavir/ritonavir. Consider therapy modification

Loratadine: Ketoconazole (Systemic) may increase the serum concentration of Loratadine. Monitor therapy

Lorlatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lorlatinib. Management: Avoid use of lorlatinib with strong CYP3A4 inhibitors. If the combination cannot be avoided, reduce the lorlatinib dose from 100 mg once daily to 75 mg once daily, or from 75 mg once daily to 50 mg once daily. Consider therapy modification

Lovastatin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lovastatin. Avoid combination

Lumacaftor and Ivacaftor: May decrease the serum concentration of Ketoconazole (Systemic). Management: Concurrent use of lumacaftor/ivacaftor and ketoconazole is not recommended. Consider an alternative antifungal such as fluconazole if appropriate. If this combination cannot be avoided, monitor patients for decreased ketoconazole efficacy. Consider therapy modification

Lumateperone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lumateperone. Avoid combination

Lumefantrine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lumefantrine. Monitor therapy

Lurasidone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lurasidone. Avoid combination

Lurbinectedin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Lurbinectedin. Avoid combination

Macitentan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Macitentan. Avoid combination

Manidipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Manidipine. Management: Consider avoiding concomitant use of manidipine and strong CYP3A4 inhibitors. If combined, monitor closely for increased manidipine effects and toxicities. Manidipine dose reductions may be required. Consider therapy modification

Maraviroc: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Maraviroc. Management: Reduce maraviroc to 150mg twice/day in adult and pediatrics weighing 40kg or more. See full interaction monograph for dose adjustments in pediatrics weighing 10 to less than 40kg. Do not use if CrCl less than 30mL/min or in those weighing less than 10 kg. Consider therapy modification

MedroxyPROGESTERone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of MedroxyPROGESTERone. Monitor therapy

Meperidine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Meperidine. Monitor therapy

Methadone: Ketoconazole (Systemic) may increase the serum concentration of Methadone. Avoid combination

Methylergonovine: Ketoconazole (Systemic) may increase the serum concentration of Methylergonovine. Avoid combination

Midazolam: Ketoconazole (Systemic) may increase the serum concentration of Midazolam. Avoid combination

Midostaurin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Midostaurin. Management: Seek alternatives to the concomitant use of midostaurin and strong CYP3A4 inhibitors if possible. If concomitant use cannot be avoided, monitor patients for increased risk of adverse reactions. Consider therapy modification

MiFEPRIStone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of MiFEPRIStone. Management: For treatment of hyperglycemia in Cushing's syndrome, start mifepristone at 300 mg/day, may titrate to a maximum of 900 mg/day. If starting a strong CYP3A4 inhibitor and taking >300 mg/day mifepristone, decrease the mifepristone dose by 300 mg/day. Consider therapy modification

Mirabegron: Ketoconazole (Systemic) may increase the serum concentration of Mirabegron. Monitor therapy

Mirodenafil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mirodenafil. Management: Consider using a lower dose of mirodenafil when used with strong CYP3A4 inhibitors. Monitor for increased mirodenafil effects/toxicities with the use of this combination. Consider therapy modification

Mirtazapine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mirtazapine. Monitor therapy

Mitotane: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Management: Doses of CYP3A4 substrates may need to be adjusted substantially when used in patients being treated with mitotane. Consider therapy modification

Mizolastine: Antifungal Agents (Azole Derivatives, Systemic) may increase the serum concentration of Mizolastine. Avoid combination

Mometasone (Oral Inhalation): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Mometasone (Oral Inhalation). Monitor therapy

Morphine (Systemic): P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Morphine (Systemic). Monitor therapy

Nadolol: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Nadolol. Monitor therapy

Naldemedine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Naldemedine. Monitor therapy

Nalfurafine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nalfurafine. Monitor therapy

Naloxegol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Naloxegol. Avoid combination

Neratinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Neratinib. Avoid combination

Nevirapine: May decrease the serum concentration of Ketoconazole (Systemic). Avoid combination

Nilotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nilotinib. Management: Avoid if possible. If combination needed, decrease nilotinib to 300 mg once/day for patients with resistant or intolerant Ph+ CML or to 200 mg once/day for patients with newly diagnosed Ph+ CML in chronic phase. Consider therapy modification

NiMODipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of NiMODipine. Avoid combination

Nintedanib: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Nintedanib. Monitor therapy

Nisoldipine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Nisoldipine. Avoid combination

Olaparib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Olaparib. Management: Avoid use of strong CYP3A4 inhibitors with olaparib, if possible. If such concurrent use cannot be avoided, the dose of olaparib tablets should be reduced to 100 mg twice daily and the dose of olaparib capsules should be reduced to 150 mg twice daily. Consider therapy modification

Oliceridine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Oliceridine. Monitor therapy

Osilodrostat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Osilodrostat. Management: Reduce osilodrostat dose by 50% during coadministration with a strong CYP3A4 inhibitor. Consider therapy modification

Ospemifene: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ospemifene. Monitor therapy

Oxybutynin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Oxybutynin. Monitor therapy

Palbociclib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Palbociclib. Management: Avoid concurrent use of strong CYP3A4 inhibitors with palbociclib when possible. If the use of a strong CYP3A4 inhibitor cannot be avoided, decrease the palbociclib dose to 75 mg/day. Consider therapy modification

Panobinostat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Panobinostat. Management: Reduce the panobinostat dose to 10 mg when it must be used with a strong CYP3A4 inhibitor. Monitor patient response to therapy closely for evidence of more severe adverse effects related to panobinostat therapy. Consider therapy modification

Parecoxib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Parecoxib. Specifically, serum concentrations of the active moiety valdecoxib may be increased. Monitor therapy

Paricalcitol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Paricalcitol. Monitor therapy

PAZOPanib: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of PAZOPanib. Avoid combination

Pemigatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pemigatinib. Management: If combined use cannot be avoided, reduce the pemigatinib dose from 13.5 mg daily to 9 mg daily, or from 9 mg daily to 4.5 mg daily. Resume prior pemigatinib dose after stopping the strong inhibitor once 3 half-lives of the inhibitor has passed. Consider therapy modification

Pexidartinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pexidartinib. Management: Avoid use of pexidartinib with strong CYP3A4 inhibitors if possible. If combined use cannot be avoided, pexidartinib dose should be reduced. Decrease 800 mg or 600 mg daily doses to 200 mg twice daily. Decrease doses of 400 mg per day to 200 mg once daily Consider therapy modification

Pimavanserin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pimavanserin. Management: Decrease the pimavanserin dose to 10 mg daily when combined with strong CYP3A4 inhibitors. Consider therapy modification

Pimecrolimus: CYP3A4 Inhibitors (Strong) may decrease the metabolism of Pimecrolimus. Monitor therapy

Pimozide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pimozide. Avoid combination

Piperaquine: CYP3A4 Inhibitors (Strong) may enhance the QTc-prolonging effect of Piperaquine. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Piperaquine. Management: Avoid concomitant use of piperaquine and strong CYP3A4 inhibitors when possible. If the combination cannot be avoided, frequent ECG monitoring is recommended due to the risk for QTc prolongation. Consider therapy modification

Polatuzumab Vedotin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Polatuzumab Vedotin. Exposure to unconjugated MMAE, the cytotoxic small molecule component of polatuzumab vedotin, may be increased. Monitor therapy

PONATinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of PONATinib. Management: Reduce the adult starting dose of ponatinib to 30 mg daily during treatment with any strong CYP3A4 inhibitor. Consider therapy modification

Pralsetinib: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Pralsetinib. Management: Avoid concomitant use if possible. If combined, reduce the pralsetinib dose. If taking 400 mg or 300 mg once daily, reduce to 200 mg once daily. If taking 200 mg once daily, reduce to 100 mg once daily. Consider therapy modification

Pranlukast: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Pranlukast. Monitor therapy

Praziquantel: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Praziquantel. Monitor therapy

PrednisoLONE (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of PrednisoLONE (Systemic). Monitor therapy

PredniSONE: CYP3A4 Inhibitors (Strong) may increase the serum concentration of PredniSONE. Monitor therapy

Propafenone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Propafenone. Monitor therapy

Proton Pump Inhibitors: May decrease the absorption of Ketoconazole (Systemic). Ketoconazole (Systemic) may increase the serum concentration of Proton Pump Inhibitors. Management: Administer ketoconazole with an acidic beverage, such as non-diet cola, to increase gastric acidity and improve absorption if concomitant use with proton pump inhibitors is necessary. Consider therapy modification

QUEtiapine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of QUEtiapine. Management: In quetiapine treated patients, reduce quetiapine to one-sixth of regular dose after starting strong CYP3A4 inhibitor. In those on strong CYP3A4 inhibitors, start quetiapine at lowest dose and up-titrate as needed. Consider therapy modification

QuiNIDine: Ketoconazole (Systemic) may enhance the QTc-prolonging effect of QuiNIDine. Ketoconazole (Systemic) may increase the serum concentration of QuiNIDine. Avoid combination

Quinidine (Non-Therapeutic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Quinidine (Non-Therapeutic). Monitor therapy

Radotinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Radotinib. Avoid combination

Ramelteon: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ramelteon. Monitor therapy

Ranolazine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ranolazine. Avoid combination

Red Yeast Rice: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Red Yeast Rice. Specifically, concentrations of lovastatin and related compounds found in Red Yeast Rice may be increased. Avoid combination

Regorafenib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Regorafenib. Avoid combination

Repaglinide: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Repaglinide. Management: The addition of a CYP2C8 inhibitor to this drug combination may substantially increase the magnitude of increase in repaglinide exposure. Monitor therapy

Retapamulin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Retapamulin. Management: Avoid this combination in patients less than 2 years old. No action is required in other populations. Monitor therapy

Ribociclib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ribociclib. Management: Avoid use of ribociclib with strong CYP3A4 inhibitors when possible; if combined use cannot be avoided, reduce ribociclib dose to 400 mg once daily. Consider therapy modification

Rifamycin Derivatives: Antifungal Agents (Azole Derivatives, Systemic) may increase the serum concentration of Rifamycin Derivatives. Only rifabutin appears to be affected. Rifamycin Derivatives may decrease the serum concentration of Antifungal Agents (Azole Derivatives, Systemic). Management: Avoid these combinations when possible. Voriconazole and isavuconazonium are considered contraindicated. Consider therapy modification

RifAXIMin: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of RifAXIMin. Monitor therapy

Rilpivirine: Ketoconazole (Systemic) may increase the serum concentration of Rilpivirine. Rilpivirine may decrease the serum concentration of Ketoconazole (Systemic). Monitor therapy

Rimegepant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Rimegepant. Avoid combination

Riociguat: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Riociguat. Management: Consider a riociguat starting dose of 0.5 mg 3 times a day when initiating riociguat in patients receiving strong CYP3A4 and P-gp inhibitors. Monitor for hypotension when these agents are combined and reduce the riociguat dose as needed. Consider therapy modification

Ripretinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ripretinib. Monitor therapy

RisperiDONE: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of RisperiDONE. Monitor therapy

Ritonavir: May increase the serum concentration of Ketoconazole (Systemic). Management: Limit the adult maximum ketoconazole dose to 200 mg/day in patients receiving ritonavir. Consider therapy modification

Rivaroxaban: Inhibitors of CYP3A4 (Strong) and P-glycoprotein may increase the serum concentration of Rivaroxaban. Avoid combination

RomiDEPsin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of RomiDEPsin. Monitor therapy

RomiDEPsin: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of RomiDEPsin. Monitor therapy

Rupatadine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Rupatadine. Avoid combination

Ruxolitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ruxolitinib. Management: This combination should be avoided under some circumstances; dose adjustments may be required in some circumstances and depend on the indication for ruxolitinib. See monograph for details. Consider therapy modification

Saccharomyces boulardii: Antifungal Agents (Systemic, Oral) may diminish the therapeutic effect of Saccharomyces boulardii. Avoid combination

Salmeterol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Salmeterol. Avoid combination

Saquinavir: May increase the serum concentration of Ketoconazole (Systemic). Ketoconazole (Systemic) may increase the serum concentration of Saquinavir. Management: Limit the adult maximum ketoconazole dose to 200 mg/day in patients receiving saquinavir/ritonavir. Consider therapy modification

Sarilumab: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy

SAXagliptin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of SAXagliptin. Management: Limit the saxagliptin dose to 2.5 mg daily when combined with strong CYP3A4 inhibitors. When using the saxagliptin combination products saxagliptin/dapagliflozin or saxagliptin/dapagliflozin/metformin, avoid use with strong CYP3A4 inhibitors. Consider therapy modification

Selpercatinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Selpercatinib. Management: Avoid combination if possible. If use is necessary, reduce selpercatinib dose as follows: from 120 mg twice/day to 40 mg twice/day, or from 160 mg twice/day to 80 mg twice/day. Consider therapy modification

Selumetinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Selumetinib. Management: Avoid concomitant use when possible. If combined, selumetinib dose reductions are recommended and vary based on body surface area and selumetinib dose. For details, see the full drug interaction monograph or selumetinib prescribing information. Consider therapy modification

Sibutramine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Sibutramine. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sibutramine. Monitor therapy

Sildenafil: Ketoconazole (Systemic) may increase the serum concentration of Sildenafil. Management: Concurrent ketoconazole is not recommended when sildenafil is used for treatment of pulmonary arterial hypertension. If sildenafil is used to treat erectile dysfunction, an initial dose of 25 mg is recommended with concurrent ketoconazole. Consider therapy modification

Silodosin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Silodosin. Avoid combination

Siltuximab: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy

Simeprevir: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Simeprevir. Avoid combination

Simvastatin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Simvastatin. Avoid combination

Sirolimus: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sirolimus. Management: Avoid concurrent use of sirolimus with strong CYP3A4 inhibitors when possible and alternative agents with lesser interaction potential with sirolimus should be considered. Concomitant use of sirolimus and voriconazole or posaconazole is contraindicated. Consider therapy modification

Sirolimus: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Sirolimus. Management: Avoid concurrent use of sirolimus with P-glycoprotein (P-gp) inhibitors when possible and alternative agents with lesser interaction potential with sirolimus should be considered. Monitor for increased sirolimus concentrations/toxicity if combined. Consider therapy modification

Solifenacin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Solifenacin. Management: Limit adult solifenacin doses to 5 mg daily and limit doses in pediatric patients to the recommended weight-based starting dose (and do not increase the dose) when combined with strong CYP3A4 inhibitors. Consider therapy modification

Sonidegib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Sonidegib. Avoid combination

SORAfenib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of SORAfenib. Monitor therapy

Sucralfate: May decrease the serum concentration of Ketoconazole (Systemic). Monitor therapy

SUFentanil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of SUFentanil. Management: If a strong CYP3A4 inhibitor is initiated in a patient on sufentanil, consider a sufentanil dose reduction and monitor for increased sufentanil effects and toxicities (eg, respiratory depression). Consider therapy modification

SUNItinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of SUNItinib. Management: Avoid when possible. If combined, decrease sunitinib dose to a minimum of 37.5 mg daily when treating GIST or RCC. Decrease sunitinib dose to a minimum of 25 mg daily when treating PNET. Monitor patients for both reduced efficacy and increased toxicities. Consider therapy modification

Suvorexant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Suvorexant. Avoid combination

Tacrolimus (Systemic): Ketoconazole (Systemic) may increase the serum concentration of Tacrolimus (Systemic). Management: Tacrolimus dose adjustment may be required; empiric dose reductions of 50% have been recommended. Monitor tacrolimus concentrations and clinical response closely. Consider therapy modification

Tacrolimus (Topical): Antifungal Agents (Azole Derivatives, Systemic) may decrease the metabolism of Tacrolimus (Topical). Applicable Isavuconazonium considerations are addressed in separate monographs. Monitor therapy

Tadalafil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tadalafil. Management: Avoid this combination in patients taking tadalafil for pulmonary arterial hypertension. In patients taking tadalafil for ED or BPH, max tadalafil dose is 2.5 mg if taking daily or 10 mg no more frequently than every 72 hours if used as needed. Consider therapy modification

Talazoparib: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Talazoparib. Monitor therapy

Tamsulosin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tamsulosin. Avoid combination

Tasimelteon: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tasimelteon. Monitor therapy

Tazemetostat: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tazemetostat. Avoid combination

Tegaserod: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Tegaserod. Monitor therapy

Telithromycin: Ketoconazole (Systemic) may increase the serum concentration of Telithromycin. Telithromycin may increase the serum concentration of Ketoconazole (Systemic). Avoid combination

Temsirolimus: Ketoconazole (Systemic) may increase serum concentrations of the active metabolite(s) of Temsirolimus. Management: Temsirolimus dose adjustments will likely be needed when starting/stopping/changing ketoconazole. Clinical data suggest temsirolimus (adult) dose reductions of around 50% should be considered, but specific guidelines are lacking. Consider therapy modification

Teneligliptin: Ketoconazole (Systemic) may increase the serum concentration of Teneligliptin. Monitor therapy

Terfenadine: Ketoconazole (Systemic) may enhance the QTc-prolonging effect of Terfenadine. Ketoconazole (Systemic) may increase the serum concentration of Terfenadine. Avoid combination

Tetrahydrocannabinol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tetrahydrocannabinol. Monitor therapy

Tetrahydrocannabinol and Cannabidiol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tetrahydrocannabinol and Cannabidiol. Monitor therapy

Tezacaftor and Ivacaftor: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tezacaftor and Ivacaftor. Management: If combined with strong CYP3A4 inhibitors, tezacaftor/ivacaftor should be administered in the morning, twice a week, approximately 3 to 4 days apart. Tezacaftor/ivacaftor dose depends on age and weight; see full Lexi-Interact monograph for details. Consider therapy modification

Thiotepa: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Thiotepa. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Thiotepa. Management: Thiotepa prescribing information recommends avoiding concomitant use of thiotepa and strong CYP3A4 inhibitors. If concomitant use is unavoidable, monitor for adverse effects and decreased efficacy. Consider therapy modification

Ticagrelor: CYP3A4 Inhibitors (Strong) may decrease serum concentrations of the active metabolite(s) of Ticagrelor. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ticagrelor. Avoid combination

Tipranavir: May increase the serum concentration of Ketoconazole (Systemic). Management: Limit ketoconazole adult maximum dose to 200 mg/day in patients treated with tipranavir. Consider therapy modification

Tocilizumab: May decrease the serum concentration of CYP3A4 Substrates (High risk with Inducers). Monitor therapy

Tofacitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tofacitinib. Management: Tofacitinib dose reductions are recommended when combined with strong CYP3A4 inhibitors. Recommended dose adjustments vary by tofacitinib formulation and therapeutic indication. See full Lexi Interact monograph for details. Consider therapy modification

Tolterodine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tolterodine. Management: The maximum recommended dose of tolterodine is 2 mg per day (1 mg twice daily for immediate-release tablets or 2 mg daily for extended-release capsules) when used together with a strong CYP3A4 inhibitor. Consider therapy modification

Tolvaptan: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Tolvaptan. Avoid combination

Topotecan: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Topotecan. Avoid combination

Toremifene: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Toremifene. Management: Use of toremifene with strong CYP3A4 inhibitors should be avoided if possible. If coadministration is necessary, monitor for increased toremifene toxicities, including QTc interval prolongation. Consider therapy modification

Trabectedin: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Trabectedin. Avoid combination

TraMADol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of TraMADol. Monitor therapy

TraZODone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of TraZODone. Management: Consider the use of a lower trazodone dose and monitor for increased trazodone effects (eg, sedation, QTc prolongation) if combined with strong CYP3A4 inhibitors. Consider therapy modification

Triamcinolone (Systemic): CYP3A4 Inhibitors (Strong) may increase the serum concentration of Triamcinolone (Systemic). Monitor therapy

Triazolam: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Triazolam. Avoid combination

Ubrogepant: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ubrogepant. Avoid combination

Udenafil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Udenafil. Avoid combination

Ulipristal: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Ulipristal. Management: This is specific for when ulipristal is being used for signs/symptoms of uterine fibroids (Canadian indication). When ulipristal is used as an emergency contraceptive, patients receiving this combo should be monitored for ulipristal toxicity. Avoid combination

Upadacitinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Upadacitinib. Monitor therapy

Valbenazine: CYP3A4 Inhibitors (Strong) may increase serum concentrations of the active metabolite(s) of Valbenazine. CYP3A4 Inhibitors (Strong) may increase the serum concentration of Valbenazine. Management: Reduce the valbenazine dose to 40 mg daily when combined with strong CYP3A4 inhibitors. Consider therapy modification

Vardenafil: Ketoconazole (Systemic) may increase the serum concentration of Vardenafil. Management: Limit Levitra (vardenafil) dose to 5 mg per 24 hours with ketoconazole 200 mg/day and 2.5 mg per 24 hours with ketoconazole 400 mg/day. Avoid concomitant use of Staxyn (vardenafil) and ketoconazole. Combined use is contraindicated outside of the US. Consider therapy modification

Vemurafenib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vemurafenib. Management: Avoid concurrent use of vemurafenib with strong CYP3A4 inhibitors when possible. If concomitant use is unavoidable, consider a vemurafenib dose reduction if clinically indicated. Consider therapy modification

Venetoclax: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Venetoclax. Management: Coadministration is contraindicated during venetoclax initiation and ramp-up in CLL/SLL patients. Reduced venetoclax doses are required during ramp-up for patients with AML, and all maintenance therapy. See full Lexi Interact monograph for details. Consider therapy modification

Venetoclax: P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of Venetoclax. Management: Reduce the venetoclax dose by at least 50% in patients requiring concomitant treatment with P-glycoprotein (P-gp) inhibitors. Resume the previous venetoclax dose 2 to 3 days after discontinuation of a P-gp inhibitor. Consider therapy modification

Verapamil: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Verapamil. Management: Consider alternatives to this combination when possible. If combined, monitor for increased verapamil effects and toxicities (eg, hypotension, bradycardia). Consider therapy modification

Vilanterol: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vilanterol. Monitor therapy

Vilazodone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vilazodone. Management: Limit the maximum vilazodone dose to 20 mg daily in patients receiving strong CYP3A4 inhibitors. The original vilazodone dose can be resumed following discontinuation of the strong CYP3A4 inhibitor. Consider therapy modification

VinBLAStine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of VinBLAStine. Monitor therapy

VinCRIStine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of VinCRIStine. Management: Seek alternatives to this combination when possible. If combined, monitor closely for vincristine toxicities (eg, neurotoxicity, gastrointestinal toxicity, myelosuppression). Consider therapy modification

VinCRIStine (Liposomal): CYP3A4 Inhibitors (Strong) may increase the serum concentration of VinCRIStine (Liposomal). Avoid combination

VinCRIStine (Liposomal): P-glycoprotein/ABCB1 Inhibitors may increase the serum concentration of VinCRIStine (Liposomal). Avoid combination

Vindesine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vindesine. Monitor therapy

Vinflunine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vinflunine. Avoid combination

Vinorelbine: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vinorelbine. Monitor therapy

Vitamin K Antagonists (eg, warfarin): Ketoconazole (Systemic) may increase the serum concentration of Vitamin K Antagonists. Monitor therapy

Vorapaxar: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Vorapaxar. Avoid combination

Voxelotor: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Voxelotor. Management: Avoid concomitant use of voxelotor and strong CYP3A4 inhibitors. If concomitant use is unavoidable, reduce the voxelotor dose to 1,000 mg once daily. Consider therapy modification

Zanubrutinib: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Zanubrutinib. Management: Decrease the zanubrutinib dose to 80 mg once daily during coadministration with a strong CYP3A4 inhibitor. Further dose adjustments may be required for zanubrutinib toxicities, refer to prescribing information for details. Consider therapy modification

Zolpidem: Ketoconazole (Systemic) may increase the serum concentration of Zolpidem. Management: Consider using a lower starting dose of zolpidem in patients receiving ketoconazole and monitor for increased zolpidem effects/toxicities if these agents are combined. Consider therapy modification

Zopiclone: CYP3A4 Inhibitors (Strong) may increase the serum concentration of Zopiclone. Management: If coadministered with strong CYP3A4 inhibitors, initiate zopiclone at 3.75 mg in adults, with a maximum dose of 5 mg. Monitor for zopiclone toxicity (eg, drowsiness, confusion, lethargy, ataxia, respiratory depression). Consider therapy modification

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

Frequency not always defined.

Cardiovascular: Orthostatic hypotension, peripheral edema

Central nervous system: Fatigue, insomnia, malaise, nervousness, paresthesia

Dermatologic: Pruritus (2%), alopecia, dermatitis, erythema, erythema multiforme, skin rash, urticaria, xeroderma

Endocrine & metabolic: Hot flash, hyperlipidemia, menstrual disease

Gastrointestinal: Nausea (3%), vomiting (3%), abdominal pain (1%), anorexia, constipation, dysgeusia, dyspepsia, flatulence, increased appetite, tongue discoloration, upper abdominal pain, xerostomia

Hematologic & oncologic: Decreased platelet count

Hepatic: Jaundice

Hypersensitivity: Anaphylactoid reaction

Neuromuscular & skeletal: Myalgia, weakness

Respiratory: Epistaxis

Miscellaneous: Alcohol intolerance

<1%, postmarketing, and/or case reports: Acute generalized exanthematous pustulosis, adrenocortical insufficiency (≥400 mg/day), anaphylactic shock, anaphylaxis, angioedema, arthralgia, azoospermia, bulging fontanel (infants), chills, cholestatic hepatitis, cirrhosis, decreased plasma testosterone (impaired at 800 mg/day), depression, diarrhea, dizziness, drowsiness, erectile dysfunction (doses >200-400 mg/day), fever, gynecomastia, headache, hemolytic anemia, hepatic failure, hepatic necrosis, hepatitis, hepatotoxicity, hypertriglyceridemia, hypersensitivity reaction, impotence, increased intracranial pressure (reversible), leukopenia, myopathy, papilledema, photophobia, prolonged QT interval on ECG, skin photosensitivity, suicidal tendencies, thrombocytopenia

ALERT: U.S. Boxed Warning

Appropriate use:

Because ketoconazole tablets have been associated with serious adverse effects, ketoconazole tablets are not indicated for the treatment of onychomycosis, cutaneous dermatophyte infections, or Candida infections. Use ketoconazole only when other effective antifungal therapy is not available or tolerated and the potential benefits are considered to outweigh the potential risks.

Hepatotoxicity:

Serious hepatotoxicity, including cases with a fatal outcome or requiring liver transplantation, has occurred with the use of oral ketoconazole. Some patients had no obvious risk factors for liver disease. Inform patients receiving this drug of the risk and closely monitor.

QT prolongation and drug interactions leading to QT prolongation:

Coadministration of the following drugs with ketoconazole is contraindicated: dofetilide, quinidine, pimozide, cisapride, methadone, disopyramide, dronedarone, and ranolazine. Ketoconazole can cause elevated plasma concentrations of these drugs and may prolong QT intervals, sometimes resulting in life-threatening ventricular dysrhythmias, such as torsades de pointes.

Warnings/Precautions

Concerns related to adverse effects:

• Adrenal suppression: High doses of ketoconazole may depress adrenocortical function; returns to baseline upon discontinuation of therapy. Recommended maximum dosing should not be exceeded. Monitor adrenal function as clinically necessary, particularly in patients with adrenal insufficiency and in patients under prolonged stress (eg, intensive care, major surgery).

• Bone fragility: In animal studies, increased long bone fragility with cases of fracture has been observed with high-dose ketoconazole. Careful dose selection may be advisable for patients susceptible to bone fragility (eg, postmenopausal women, elderly).

• Hypersensitivity reactions: Cases of hypersensitivity reactions (including rare cases of anaphylaxis) have been reported; some reactions occurred after the initial dose.

• Myopathy: Coadministration with HMG-CoA reductase inhibitors (eg, lovastatin, simvastatin) may increase the risk of myopathy. Concomitant use is contraindicated.

• Sedation: Coadministration with midazolam, triazolam, and alprazolam may result in elevated plasma concentrations of the benzodiazepines, leading to prolonged hypnotic and sedative effects. Concomitant use is contraindicated.

Disease-related concerns:

• Achlorhydria: Absorption is reduced in patients with achlorhydria; administer with acidic liquids (eg, soda pop). Avoid concomitant use of drugs that decrease gastric acidity (eg, proton pump inhibitors, antacids, H2-blockers).

• CNS infections: Ketoconazole has poor penetration into cerebral-spinal fluid and should not be used to treat fungal meningitis.

• Hepatic impairment: [US Boxed Warning]: Ketoconazole has been associated with hepatotoxicity, including fatal cases and cases requiring liver transplantation; some patients had no apparent risk factors for hepatic disease. Patients should be advised of the hepatotoxicity risks and monitored closely. Toxicity was observed after a median duration of therapy of ~4 weeks, but has also been noted after as little as 3 days; may occur when patients receive high doses for short durations or low doses for long durations. Cases have been reported in patients treated with ketoconazole for onychomycosis, cutaneous dermatophyte infections, or Candida infections. Use with caution in patients with preexisting hepatic impairment, those on prolonged therapy and/or taking other hepatotoxic drugs concurrently. Hepatic dysfunction is typically (but not always) reversible upon discontinuation. Obtain liver function tests at baseline and frequently throughout therapy; serum ALT should be monitored weekly throughout therapy. Discontinue therapy for elevated hepatic enzymes that persist or worsen or if accompanied by signs/symptoms (eg, jaundice, nausea/vomiting, dark urine) of hepatic injury.

• Prostate cancer: In European clinical trials of men with metastatic prostate cancer, fatalities were reported in a small number of study participants within 14 days of initiating high-dose ketoconazole (1,200 mg daily); a causal effect has not been established.

Concurrent drug therapy issues:

• QT prolongation: [US Boxed Warning]: Concomitant use with cisapride, disopyramide, dofetilide, dronedarone, methadone, pimozide, quinidine, and ranolazine is contraindicated due to the possible occurrence of life-threatening ventricular arrhythmias such as torsade de pointes.

Other warnings/precautions:

• Appropriate use: [US Boxed Warning]: Ketoconazole tablets are not indicated for the treatment of onychomycosis, cutaneous dermatophyte infections, or Candida infections. Use only when other effective antifungal therapy is unavailable or not tolerated and the benefits of ketoconazole treatment are considered to outweigh the risks. Ketoconazole oral tablets are only approved to treat systemic fungal infections.

Monitoring Parameters

Hepatic function tests (baseline and frequently during therapy), including weekly ALT for the duration of treatment; Canadian labeling recommends monitoring hepatic function at baseline, at weeks 2 and 4, and monthly thereafter; calcium and phosphorous (periodically with long-term use); adrenal function as clinically necessary

Reproductive Considerations

Women with Cushing syndrome often experience oligomenorrhea or amenorrhea due to the pathological cortisol excess associated with this disease. Patients treated with ketoconazole may experience a decrease in ovulatory disturbances and should be informed of the potential return of fertility (Berwaerts 1999; Boronat 2011; Costenaro 2015).

The use of ketoconazole in male patients has been associated with decreased testosterone concentrations. Adverse effects have included reversible gynecomastia, oligospermia, impotence, and decreased libido.

Pregnancy Considerations

Due to the teratogenicity reported in animal reproduction studies and its antiandrogenic effects, ketoconazole is not recommended for the treatment of systemic fungal infections in pregnant women. Other agents are more frequently used to treat Cushing syndrome in pregnancy (Bronstein 2015; Brue 2018; Galgiani 2016; HHS [OI adult 2019]; IDSA [Galgiani 2016]; Pilmis 2015).

Patient Education

What is this drug used for?

• It is used to treat fungal infections.

• It may be given to you for other reasons. Talk with the doctor.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Abdominal pain

• Nausea

• Diarrhea

• Headache

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Liver problems like dark urine, fatigue, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or yellow skin.

• Adrenal gland problems like severe nausea, vomiting, severe dizziness, passing out, muscle weakness, severe fatigue, mood changes, lack of appetite, or weight loss.

• Fast heartbeat

• Abnormal heartbeat

• Sensitivity to lights

• Enlarged breasts

• Tongue discoloration

• Menstrual changes

• Chills

• Muscle pain

• Muscle weakness

• Sexual dysfunction

• Decreased sperm counts

• Burning or numbness feeling

• Swelling of arms or legs

• Bruising

• Bleeding

• Dizziness

• Chest pain

• Passing out

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Frequently Asked Questions