Ketoconazole

Ketoconazole is an antifungal medication in the imidazole class. It works by inhibiting the fungal cytochrome P450 enzyme lanosterol 14α-demethylase, which blocks ergosterol synthesis and disturbs the fungal cell membrane. It has activity against a range of yeasts and dermatophytes.

Ketoconazole is available in topical forms (creams, lotions, gels, foams, and a shampoo) used to treat cutaneous fungal infections such as tinea infections, candidal infections of the skin, and seborrheic dermatitis or dandruff. It is also available orally for systemic fungal infections, but systemic use is limited in many countries due to safety concerns; topical therapy remains the primary option for most conditions. Some formulations are used off-label for other mucosal infections under medical supervision.

Safety and regulatory considerations are notable with ketoconazole. Systemic ketoconazole carries a significant risk of hepatotoxicity and can cause adrenal suppression with long-term use. It is a potent inhibitor of cytochrome P450 enzymes and can interact with many medications, leading to serious drug interactions. Because of these risks, systemic use is generally reserved for situations where other antifungals are ineffective or inappropriate. Topical ketoconazole is associated with fewer systemic effects but can cause local irritation or allergic reactions. It should be used with caution in liver disease, pregnancy, or when combined with other hepatotoxic drugs, and patients should be monitored for signs of liver injury.

Brand names include Nizoral, among others.