title: In vitro metabolism of rivoglitazone, a novel peroxisome proliferator-activated receptor γ agonist, in rat, monkey, and human liver microsomes and freshly isolated hepatocytes.
abstract: The in vitro metabolism of rivoglitazone, (RS)-5-{4-[(6-methoxy-1-methyl-1H-benzimidazol-2-yl)methoxy]benzyl}-1,3-thiazolidine-2,4-dione monohydrochloride, a novel thiazolidinedione (TZD) peroxisome proliferator-activated receptor γ selective agonist, was studied in liver microsomes and freshly isolated hepatocytes of rat, monkey, and human as well as cDNA-expressed human cytochrome P450 (P450) and UDP-glucuronosyltransferase (UGT) enzymes. Fourteen metabolites were detected, and these structures were elucidated by liquid chromatography-tandem mass spectrometry. Five initial metabolic pathways of rivoglitazone consisting of four oxidation pathways and one N-glucuronidation pathway were predicted in correspondence with those proposed for in vivo studies using rats and monkeys. In metabolization using liver microsomes, the TZD ring-opened mercapto amide (M22) and TZD ring-opened mercapto carboxylic acid (M23) were identified as the primary metabolite of the TZD ring-opening pathway and its sequential metabolite, which have not been detected previously from in vivo studies. Combination with S-adenosyl-L-methionine was useful to obtain the sequential S-methylated metabolites from the oxidative metabolites. N-Glucuronide and sequential TZD ring-opened metabolites were also found in liver microsomes in the presence of UDP-glucuronic acid. The O-demethyl-O-sulfate (M11), which is the major in vivo metabolite in rats and monkeys, was detected in all species of hepatocytes. In addition, a TZD ring-opened S-cysteine conjugate (M15) was detected in human hepatocytes. From these results, the in vivo metabolic pathways in humans were predicted to be the four oxidation and one N-glucuronidation pathways. The four oxidative metabolites were formed by multiple human P450 enzymes, and N-glucuronide was formed by UGT1A3 and UGT2B7.
authors.affiliation: Drug Metabolism and Pharmacokinetics Research Laboratories, Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo, 140-8710, Japan. uchiyama.minoru.fe@daiichisankyo.co.jp
authors.forename: Minoru
authors.initials: M
authors.lastname: Uchiyama
authors.forename: Hiroko
authors.initials: H
authors.lastname: Koda
authors.forename: Thomas
authors.initials: T
authors.lastname: Fischer
authors.forename: Juergen
authors.initials: J
authors.lastname: Mueller
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Yamamura
authors.forename: Minoru
authors.initials: M
authors.lastname: Oguchi
authors.forename: Haruo
authors.initials: H
authors.lastname: Iwabuchi
authors.forename: Osamu
authors.initials: O
authors.lastname: Okazaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Izumi
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid; D000882:Haplorhini; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D007004:Hypoglycemic Agents / Q000493:pharmacokinetics*; D066298:In Vitro Techniques; D008862:Microsomes, Liver / Q000378:metabolism*; D047495:PPAR gamma / Q000819:agonists*; D051381:Rats; D053719:Tandem Mass Spectrometry; D045162:Thiazolidinediones / Q000493:pharmacokinetics*
chemical_list: D007004:Hypoglycemic Agents; D047495:PPAR gamma; D045162:Thiazolidinediones; C521549:rivoglitazone