RESUMO
BACKGROUND: Carbamazepine is associated with clinically relevant drug interactions especially with macrolide antibiotics such as troleandomycin and erythromycin. These drugs inhibit the metabolism of carbamazepine. Clarithromycin, a macrolide antibiotic similar to erythromycin, is widely used to treat respiratory tract infections and is used for the treatment of atypical mycobacterial infections and Helicobacter pylori-associated peptic ulcer disease. METHODS: To report an interaction between carbamazepine and clarithromycin, we present a study that includes three regular attenders at the epilepsy department of Montpellier and seven cases reported by the French national drug safety center. RESULTS: In patients receiving carbamazepine alone or in combination with other drugs, administration of clarithromycin led to a transitory overdosage (ataxia, dizziness, diplopia, nausea, vomiting, drowsiness). Blood level was available in 8 patients with a concentration of carbamazepine ranging from 13.3 to 28.5 mg/l. CONCLUSION: Carbamazepine is extensively metabolized by cytochrome P450 enzymes, especially CYP34A. As clarithromycin is also metabolized by CYP3A4, this drug has the propensity to inhibit the metabolism of carbamazepine. Clarithromycin should be thus avoided in patients taking carbamazepine.
