Major
Amlodipine × Ketoconazole
Calcium channel blockers (dihydropyridines)×Systemic antimycotics. Imidazole derivatives
Mechanism
Ketoconazole is a strong CYP3A4 inhibitor – the main amlodipine metabolic route. Amlodipine plasma levels rise 2- to 3-fold; symptomatic hypotension and acute kidney injury risk.
Symptoms
Blood pressure drop: postural dizziness, syncope. Ankle oedema (typical of amlodipine), facial flushing, reflex tachycardia are possible.
Management
Avoid the combination. Alternative antifungals: terbinafine for dermatophytosis or echinocandins for systemic mycoses. If ketoconazole is needed, halve amlodipine.