title: Metabolism of the antianxiety drug buspirone in the rat.
abstract: The metabolism of an orally administered, 10-mg single dose of the antianxiety drug buspirone was studied in the rat. Samples of bile and urine were collected for 6 hr and were treated with beta-glucuronidase/arylsulfatase. The deconjugated metabolites were isolated and purified by HPLC. Structural analysis was carried out by combined gas chromatography/electron impact mass spectrometry as their trimethylsilyl derivatives and by 1H-NMR spectroscopy. Structures of the metabolites were further confirmed by co-elution on HPLC with authentic standards when possible. In addition to the already known metabolites 5-hydroxy-buspirone and 1-pyrimidinylpiperazine, seven major metabolites were unambiguously identified together with unchanged drug. Ten minor metabolites were partially characterized. Hydroxylation alpha to the glutaramidyl carbon at the 6'-position on the bicyclo ring system, hydroxylation on the pyrimidine aromatic ring, and N-dealkylation of the butyl side chain were observed as major routes of metabolism. Minor routes of metabolism observed were: 3'-hydroxylation on the bicyclo ring system and formation of the methylated catechol derivatives. The identified metabolites accounted for greater than 90% of the total metabolites excreted in the rat bile and urine samples.
authors.affiliation: Department of Chemistry, Vanderbilt University, Nashville, TN 37232.
authors.forename: H K
authors.initials: HK
authors.lastname: Jajoo
authors.forename: R F
authors.initials: RF
authors.lastname: Mayol
authors.forename: J A
authors.initials: JA
authors.lastname: LaBudde
authors.forename: I A
authors.initials: IA
authors.lastname: Blair
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism; D001711:Biotransformation; D002065:Buspirone / Q000378:metabolism* / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002065:Buspirone