Major
Carbamazepine × Clarithromycin
Antiepileptics. Carboxamide derivatives×Macrolide antibiotic
Mechanism
Clarithromycin blocks CYP3A4 – the main carbamazepine metabolic route. Carbamazepine plasma levels rise by 30–50%, with neurotoxicity risk.
Symptoms
Ataxia, diplopia, nausea, drowsiness, tremor. Severe cases include cardiac conduction abnormalities and coma. Symptoms appear within 3–5 days of co-administration.
Management
Avoid the combination. Alternative antibiotics: azithromycin or doxycycline (minimal CYP3A4 impact). If clarithromycin is needed, measure carbamazepine plasma levels at days 3 and 7.