Demethylation metabolism of roxithromycin in humans and rats

AIM: To investigate the demethylated metabolites of roxithromycin (RXM) in humans and rats, and to study the antibiotic activity of these metabolites in vitro. METHODS: The demethylated metabolites of RXM in humans and in rat s were identified by liquid chromatography-mass spectrometry (LC-MS), and t he in vitro antibiotic activities of them against three standard strains we re also studied compared with those of the parent drug and some other metab olites of RXM. RESULTS: O-Demethylation of RXM was one of the main metaboli c routes of RXM in humans, whereas N-demethylation metabolism was more pred ominant in rats. O-Demethyl-RXM appeared to be equally effective with RXM. CONCLUSION: The O-demethyl-RXM was an active metabolite in humans, and ther e were some species differences in RXM demethylation metabolism between hum ans and rats.