title: Sex differences in the metabolism of (+)-S-145, a novel thromboxane A2 receptor antagonist in rat.
abstract: 1. After the oral administration of 5 mg/kg S-1452 to rat, the plasma levels of (+)-S-145 were similar between the male and female, but there were sex differences in the profiles of its beta-oxidized and hydroxylated metabolites in plasma. 2. beta-Oxidation of (+)-S-145 determined in vitro was slightly higher in the female than in the male, and agreed with the plasma levels of the beta-oxidized metabolites. 3. 5-Hydroxylation activities of (+)-S-145 and beta-oxidized metabolites by rat liver microsomes were significantly higher in the male than in the female, but marked sex differences were not observed in 6-hydroxylation activities. These results revealed that differences in monooxygenase activities directly account for the sex differences in the plasma level of 5-hydroxylated metabolites, and that the peroxisomal beta-oxidation enzyme system also affected the plasma level of 6-hydroxylated metabolites. 4. Biliary excretion was higher in the male than in the female, and quantitative identification of metabolites in bile indicated that this was based on the prominent excretion of taurine conjugates in the male rat. This conclusion was supported by the fact that taurine conjugation activity was higher in male liver homogenates than in the female.
authors.affiliation: Department of Drug Metabolism and Disposition, Shionogi & Co., Ltd, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: R
authors.initials: R
authors.lastname: Norikura
authors.forename: M
authors.initials: M
authors.lastname: Nakanishi
authors.forename: A
authors.initials: A
authors.lastname: Touchi
authors.forename: T
authors.initials: T
authors.lastname: Yoshimori
authors.forename: T
authors.initials: T
authors.lastname: Murakami
authors.forename: T
authors.initials: T
authors.lastname: Baba
authors.forename: K
authors.initials: K
authors.lastname: Mizojiri
authors.forename: T
authors.initials: T
authors.lastname: Matsubara
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism; D001643:Bridged Bicyclo Compounds / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D002250:Carbon Radioisotopes; D005229:Fatty Acids, Monounsaturated / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D005260:Female; D006900:Hydroxylation; D008297:Male; D008830:Microbodies / Q000201:enzymology; D008862:Microsomes, Liver / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism; D010084:Oxidation-Reduction; D011448:Prostaglandin Antagonists / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors*; D012727:Sex Characteristics; D013654:Taurine / Q000378:metabolism
chemical_list: D001643:Bridged Bicyclo Compounds; D002250:Carbon Radioisotopes; D005229:Fatty Acids, Monounsaturated; D011448:Prostaglandin Antagonists; D017482:Receptors, Thromboxane; C056566:S 145; D013654:Taurine; D006899:Mixed Function Oxygenases