Major
Amlodipine × Clarithromycin
Calcium channel blockers (dihydropyridines)×Macrolide antibiotic
Mechanism
Clarithromycin blocks CYP3A4 – the main amlodipine metabolic route. Amlodipine plasma levels rise by 50–60%. Symptomatic hypotension and acute kidney injury have been reported in older patients.
Symptoms
Blood pressure drop: postural dizziness, syncope. Ankle oedema (typical of amlodipine), facial flushing, reflex tachycardia are possible.
Management
During clarithromycin therapy, halve amlodipine and monitor blood pressure. Alternative antibiotics: azithromycin or doxycycline (minimal CYP3A4 effect).
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.