Fluconazole × Simvastatin

Fluconazole at 200 mg/day or above moderately inhibits CYP3A4 – the main simvastatin metabolic route. Simvastatin plasma levels rise 2- to 3-fold, with increased myopathy risk.

Pain and weakness in large muscle groups (thighs, shoulders, calves), dark urine, elevated creatine kinase. Severe cases progress to rhabdomyolysis with acute kidney injury. Symptoms appear within 1–4 weeks of co-administration.

For short fluconazole courses (up to 7 days), hold simvastatin or halve the dose. For prolonged systemic therapy, switch to pravastatin/rosuvastatin or use an alternative antifungal (echinocandins).