Critical
Carbamazepine × Dronedarone
Antiepileptics. Carboxamide derivatives×Class III antiarrhythmic
Mechanism
Carbamazepine is a strong CYP3A4 inducer. It accelerates dronedarone clearance: levels drop by 80% and antiarrhythmic effect is lost. FDA Multaq Section 4.3 specifically lists strong CYP3A4 inducers (rifampicin, carbamazepine, phenobarbital).
Symptoms
First, recurrence of atrial fibrillation symptoms: palpitations, irregular pulse, fatigue, dyspnoea. Possible rhythm breakthroughs requiring admission.
Management
The combination is not prescribed. During carbamazepine therapy, switch to amiodarone (less affected by CYP3A4 induction) or rhythm control via catheter ablation. Alternative anticonvulsants: levetiracetam, lamotrigine (no CYP3A4 induction).