Helicobacter pylori gastritis therapy with omeprazole and clarithromycin increases serum carbamazepine levels.

An antibiotic combination that includes a proton pump inhibitor such as omeprazole and an antibiotic such as clarithromycin is likely to become the new standard regimen for treatment of Helicobacter pylori gastritis because this combination is extremely effective and very well tolerated. The current report highlights a potentially significant pharmakokinetic drug interaction between clarithromycin and carbamazepine in two patients with long-standing epilepsy who were given such therapy for Helicobacter pylori gastritis. In both cases, clarithromycin therapy was temporally related to an increase in serum carbamazepine levels, which returned to the therapeutic range following cessation of clarithromycin therapy. The potential implications of this newly recognized drug interaction are discussed.