Major
carvedilol × diltiazem
Alpha and beta blocker (non-selective β + α1)×Calcium channel blocker, non-DHP (benzothiazepine derivative)
Mechanism
Non-dihydropyridine calcium channel blocker (diltiazem) + beta-blocker (carvedilol) – additive AV node blockade and negative inotropic effect. Carvedilol's α1-blockade amplifies hypotension.
Symptoms
Bradycardia (heart rate below 50/min), dizziness, syncope. ECG: first- to second-degree AV block. Older patients: fall risk.
Management
Avoid the combination. Alternative for combined heart failure and angina: carvedilol + amlodipine (dihydropyridine, no AV effect) or diltiazem with carvedilol withdrawn.
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.