title: Application of LC-NMR for the study of the volatile metabolite of MK-0869, a substance P receptor antagonist.
abstract: LC-NMR was applied to identify the polar volatile metabolite of MK-0869. MK-0869, a morpholine-based compound containing a triazolone ring, is a very potent NK(1) receptor antagonist. Currently, it is in development as an anti-emesis agent in chemotherapy treatments. The primary metabolites of MK-0869, M1 and M2, are non-polar and lack the triazolone ring. Incubation of [14C]M1 with liver microsomes from male rats produced a very polar and volatile metabolite, M3. Analysis was not possible by LC-MS or by conventional NMR because of poor ionization, small molecular weight and volatility, leaving chemical derivatization and LC-NMR as alternative methods. Reduction of M3 with NaBH(4) resulted in a derivative that had the same retention time as p-fluorophenylethylene glycol on HPLC. A small aliquot of the solution containing M3 was passed through the LC of the LC-NMR system, which was connected on-line with a radioactivity detector. The simultaneous UV and radioactivity chromatograms thus identified the chromatographic UV peak that was associated with the metabolite. Analysis was carried out by stop-flow on another portion of this fraction. From the chemical derivatization and the analysis by LC-NMR, M3 is shown to be p-fluoro-alpha-hydroxyacetophenone. Further studies using LC-NMR showed that M3 could be generated from both M1 and M2 in NADPH-dependant reactions catalyzed by microsomes containing recombinant human CYP2C19, CYP1A2 or CYP3A4.
authors.affiliation: Department of Drug Metabolism, Merck Research Laboratories, P.O. Box 2000, RY80L-109, Rahway, NJ 07065, USA. maria_silva1@merck.com
authors.forename: Maria Victoria Silva
authors.initials: MV
authors.lastname: Elipe
authors.forename: Su Er W
authors.initials: SE
authors.lastname: Huskey
authors.forename: Bing
authors.initials: B
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000932:Antiemetics / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D000077608:Aprepitant; D002853:Chromatography, Liquid / Q000379:methods; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008862:Microsomes, Liver / Q000201:enzymology; D009025:Morpholines / Q000037:antagonists & inhibitors*; D064729:Neurokinin-1 Receptor Antagonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D014230:Triazoles / Q000037:antagonists & inhibitors*
chemical_list: D000932:Antiemetics; D007527:Isoenzymes; D009025:Morpholines; D064729:Neurokinin-1 Receptor Antagonists; D014230:Triazoles; D000077608:Aprepitant; D003577:Cytochrome P-450 Enzyme System