Major
Ketoconazole × Rifampicin
Systemic antimycotics. Imidazole derivatives×Antituberculous antibiotic
Mechanism
Dual mechanism. Rifampicin strongly induces CYP3A4, which partly metabolises ketoconazole. Ketoconazole plasma levels fall by 50–80%; antifungal efficacy is lost.
Symptoms
Recurrence of mycosis symptoms: ongoing fever, skin or mucosal lesions; in immunocompromised patients, risk of systemic mycosis progression.
Management
The combination is not prescribed. Alternative antifungal during anti-TB therapy: echinocandins (micafungin, caspofungin; resistant to CYP3A4 induction) or terbinafine for dermatophytosis.