APPLICATION OF LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY ANALYSES TO THE CHARACTERIZATION OF NOVEL GLYBURIDE METABOLITES FORMED IN-VITRO

The application of bench-top ion-trap atmospheric pressure ionization mass spectrometry in the characterization of in vitro metabolites of g lyburide is discussed. The metabolites formed in vitro by rat, dog,mon key and human liver microsomes were separated by reversed-phase high-p erformance liquid chromatography (HPLC) and characterized by mass spec trometry (MS)'' experiments. The utility of data dependent MS1-MS2-MS3 analyses, where the mass spectrometer makes ''real-time'' decisions a bout the experiment to be performed, are described using the character ization of two novel metabolites of glyburide as an example. The metab olite profiles from each species were similar. Six cyclohexyl hydroxyl ation products were detected, as well as two novel monooxygenation pro ducts formed via hydroxylation of the ethyl chain at the benzylic posi tion, and alpha to the amide nitrogen. The ion-trap with electrospray ionization proved to be a sensitive and reliable HPLC detection system that provided important chemical structure information. (C) 1998 Else vier Science B.V.