5-n-Butyl-4-{4-[2-(1H-tetrazole-5-yl)-1H-pyrrol-1-yl]phenylmethyl}-2,4-dihydro-2-(2,6-dichloridephenyl)-3H-1,2,4-triazol-3-one (1b), a new non-peptide angiotensin type 1 receptor antagonist, has been observed to play a positive role in the treatment of hypertension in preclinical tests. Rats were dosed with the drug, and the major metabolites in the bile were separated by gradient elution high-performance liquid chromatography. HPLC-diode array detection-mass spectrometry, HPLC-electrospray ionization MS/MS methods in negative ion mode and collision-induced dissociation were used to elucidate the structures of the major metabolites of 1b. One dihydroxylated 1b (M1), two monohydoxylated 1b (M2, M3) and one 1b monoglucuronide (M5) were found in male rat bile; however, three monohydoxylated 1b (M2, M3, M4) and one 1b monoglucuronide (M5) were found in female rat bile. These metabolites greatly differ in amount between male and female rat bile.
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