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ANTIINFECTIVES FOR SYSTEMIC USE › ANTIMYCOTICS FOR SYSTEMIC USE › ANTIMYCOTICS FOR SYSTEMIC USE › Imidazole derivatives
ketoconazole
J02AB02
Forms & Strengths
- Oral tablet: 200 mg
- Topical cream: 2%
- Topical shampoo: 2%, 1%a
Adult Dosing
- Systemic (off-label/historical due to toxicity): 200 to 400 mg once daily for systemic fungal infections
- Topical cream: Apply to affected skin once or twice daily
- Topical shampoo: Apply to scalp twice weekly for up to 4 weeks
Pediatric Dosing
- Systemic: Not recommended due to high risk of hepatotoxicity and adrenal suppression
- Topical: Safety and efficacy not well established in neonates/infants
Indications
- Severe systemic fungal infections (historical/restricted use when other antifungals fail)
- Topical treatment of tinea corporis, tinea cruris, tinea pedis, and cutaneous candidiasis
- Topical treatment of seborrheic dermatitis
Mechanism of Action
- Inhibits fungal cytochrome P450 14-alpha-demethylase (CYP51)
- Blocks conversion of lanosterol to ergosterol, disrupting fungal cell membrane synthesis and permeability
Contraindications
- Acute or chronic liver disease
- Hypersensitivity to ketoconazole or any component
- Co-administration with CYP3A4 substrates prone to QT prolongation (e.g., dofetilide, quinidine, pimozide, cisapride)
- Co-administration of oral tablets with simvastatin, lovastatin, or oral triazolam
Adverse Reactions
- Hepatotoxicity (potentially fatal, risk highest with oral formulation)
- Adrenal insufficiency and decreased testosterone synthesis (gynecomastia, impotence)
- Nausea, vomiting, abdominal pain, diarrhea
- Headache, dizziness
- Topical: application site burning, pruritus, erythema, contact dermatitis
Drug Interactions
- Potent CYP3A4 inhibitor: significantly increases concentrations of co-administered substrates (e.g., tacrolimus, cyclosporine, anticoagulants)
- Gastric acid reducers (antacids, H2 blockers, PPIs): significantly decrease ketoconazole oral absorption
- Hepatotoxic drugs: concurrent use increases the risk of severe liver injury
- QT-prolonging agents: increased risk of ventricular arrhythmias
Curated Content: Needs Vetting Before Put to Clinical Use