ANALYSIS OF URINARY AND BILIARY METABOLITES OF 4-METHYLPHENYL)PHENYLMETHOXY-1-PIPERIDINYL]BUTYRIC ACID IN RATS BY LIQUID-CHROMATOGRAPHY FRIT-FAST ATOM BOMBARDMENT MASS-SPECTROMETRY())

The urinary and biliary metabolites of 4-methylphenyl)phenylmethoxy-1- piperidinyl]butyric acid [(+)-MPPB] were examined in rapid-metabolizin g (RM) and slow-metabolizing (SM) male Sprague-Dawley rats by means of liquid chromatography-frit-fast atom bombardment mass spectrometry. I n the RM-phenotyped rats, unchanged (+)-MPPB could not be detected in urine or bile, but 4-carboxyphenyl-MPPB was detected in bile. In the S M-phenotyped rats, unchanged(+)-MPPB was detected in bile and unchange d (+)-MPPB and beta-oxidized MPPB in urine. Thus, the inter-individual difference in(+)-MPPB metabolism in rats was confirmed in vivo.