MajorClass III antiarrhythmics (Vaughan Williams)×Antiepileptics. Carboxamide derivatives
Updated · Methodology
Mechanism
Dual mechanism. Carbamazepine induces CYP3A4 and lowers amiodarone levels. Amiodarone blocks CYP3A4 and partially suppresses carbamazepine metabolism, so carbamazepine plasma levels may rise.
Symptoms
From amiodarone fall: atrial fibrillation symptoms return. From carbamazepine rise: ataxia, diplopia, nausea, hyponatraemia, drowsiness.
Management
Avoid the combination. Alternative anticonvulsants without induction: levetiracetam, lamotrigine. Alternative antiarrhythmic: beta-blocker for rate control or catheter ablation. If unavoidable, check carbamazepine plasma levels at 1–2 weeks.
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.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Tegretol (carbamazepine) prescribing information (2009)– ; DailyMed setid 8d409411-aa9f-4f3a-a52c-fbcb0c3ec053
- AEMPS: Ficha técnica: Carbamazepina (nº registro 62621), sección 4.4 (2025)– AEMPS, CIMA, nº registro 62621, revisión 06/2025, sección 4.4