IMPROVED DETECTION AND DETERMINATION OF CARBAMAZEPINE AND OXCARBAZEPINE AND THEIR METABOLITES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

An HPLC assay for carbamazepine or oxcarbazepine (OXC) and six of thei r metabolites in one run was applied to 35 clinical samples from patie nts receiving monotherapy. This rapid and economical method, utilizing a simple one-step extraction with methyl tert.-butyl ether before the run, showed recoveries of 77-108%, except for 43% for 10,11-trans-dih ydroxy-10,11-dihydrocarbamazepine, from 500-mu l samples, with detecti on limits of 8-12 ng/ml and limits of quantification of 14-55 ng/ml de pending on the compound. Indication of a new OXC metabolite, 3-hydroxy carbamazepine, was found in 2/12 patients.