title: Plasma stability-dependent circulation of acyl glucuronide metabolites in humans: how circulating metabolite profiles of muraglitazar and peliglitazar can lead to misleading risk assessment.
abstract: Muraglitazar and peliglitazar, two structural analogs differing by a methyl group, are dual peroxisome proliferator-activated receptor-α/γ activators. Both compounds were extensively metabolized in humans through acyl glucuronidation to form 1-O-β-acyl glucuronide (AG) metabolites as the major drug-related components in bile, representing at least 15 to 16% of the dose after oral administration. Peliglitazar AG was the major circulating metabolite, whereas muraglitazar AG was a very minor circulating metabolite in humans. Peliglitazar AG circulated at lower concentrations in animal species than in humans. Both compounds had a similar glucuronidation rate in UDP-glucuronic acid-fortified human liver microsomal incubations and a similar metabolism rate in human hepatocytes. Muraglitazar AG and peliglitazar AG were chemically synthesized and found to be similarly oxidized through hydroxylation and O-demethylation in NADPH-fortified human liver microsomal incubations. Peliglitazar AG had a greater stability than muraglitazar AG in incubations in buffer, rat, or human plasma (pH 7.4). Incubations of muraglitazar AG or peliglitazar AG in plasma produced more aglycon than acyl migration products compared with incubations in the buffer. These data suggested that the difference in plasma stability, not differences in intrinsic formation, direct excretion, or further oxidation of muraglitazar AG or peliglitazar AG, contributed to the observed difference in the circulation of these AG metabolites in humans. The study demonstrated the difficulty in doing risk assessment based on metabolite exposure in plasma because the more reactive muraglitazar AG would not have triggered a threshold of concern based on the recent U.S. Food and Drug Administration guidance on Metabolites in Safety Testing, whereas the more stable peliglitazar AG would have.
authors.affiliation: Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Research and Development, Princeton, New Jersey 08543, USA.
authors.forename: Donglu
authors.initials: D
authors.lastname: Zhang
authors.forename: Nirmala
authors.initials: N
authors.lastname: Raghavan
authors.forename: Lifei
authors.initials: L
authors.lastname: Wang
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Xue
authors.forename: Mary
authors.initials: M
authors.lastname: Obermeier
authors.forename: Stephanie
authors.initials: S
authors.lastname: Chen
authors.forename: Shiwei
authors.initials: S
authors.lastname: Tao
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Peter T
authors.initials: PT
authors.lastname: Cheng
authors.forename: Wenying
authors.initials: W
authors.lastname: Li
authors.forename: Ragu
authors.initials: R
authors.lastname: Ramanathan
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yang
authors.forename: W Griffith
authors.initials: WG
authors.lastname: Humphreys
mesh_terms: D000328:Adult; D000818:Animals; D001646:Bile / Q000737:chemistry / Q000378:metabolism; D004355:Drug Stability; D020719:Glucuronides / Q000097:blood* / Q000378:metabolism; D005998:Glycine / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008252:Macaca fascicularis; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism; D010080:Oxazoles / Q000097:blood / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010084:Oxidation-Reduction; D047493:PPAR alpha / Q000819:agonists / Q000378:metabolism; D047495:PPAR gamma / Q000819:agonists / Q000378:metabolism; D051381:Rats; D018570:Risk Assessment; D014535:Uridine Diphosphate Glucuronic Acid / Q000378:metabolism; D055815:Young Adult
chemical_list: D020719:Glucuronides; D010080:Oxazoles; D047493:PPAR alpha; D047495:PPAR gamma; D014535:Uridine Diphosphate Glucuronic Acid; C557782:peliglitazar; D005998:Glycine; C500085:muraglitazar