Identification of phase I and phase II metabolites of ketobemidone in patient urine using liquid chromatography-electrospray tandem mass spectrometry

Ketobemidone and five of its phase I metabolites were identified in the uri ne of four patients post intravenous administration of Ketogan Novum((R)). Furthermore, indications of the presence of the glucuronide conjugates of k etobemidone and norketobemidone is presented. Both hydrolyzed (P-glucuronid ase) and unhydrolyzed human urine was extracted on a mixed-mode slightly po lar cation-exchange SPEC cartridge prior to analysis with LC-ESI-MS-MS. The phase I metabolites were identified by comparison of their daughter spectr a with those of synthesized standards. The glucuronides were identified by their molecular mass and interpretation of the daughter spectra, as no stan dards were available for these compounds. (C) 2001 Elsevier Science B.V. Al l rights reserved.