title: Determination of degradation pathways and kinetics of acyl glucuronides by NMR spectroscopy.
abstract: Acyl glucuronides have been implicated in the toxicity of many xenobiotics and marketed drugs. These toxicities are hypothesized to be a consequence of covalent binding of the reactive forms of the acyl glucuronide to proteins. Reactive intermediates of the acyl glucuronide arise from the migration of the aglycone leading to other positional and stereoisomers under physiological conditions. In order to screen for the potential liabilities of these metabolites during the early phase of pharmaceutical development, an NMR method based on the disappearance of the anomeric resonance of the O-1-acyl glucuronide was used to monitor the degradation kinetics of 11 structurally diverse acyl glucuronides, including those produced from the known nonsteroidal anti-inflammatory drugs (NSAIDs). The acyl glucuronides were either chemically synthesized or were isolated from biological matrices (bile, urine, and liver microsomal extracts). The half-lives attained utilizing this method were found to be comparable to those reported in the literature. NMR analysis also enabled the delineation of the two possible pathways of degradation: acyl migration and hydrolytic cleavage. The previously characterized 1H resonances of acyl migrated products are quite distinguishable from those that arise from hydrolysis. The NMR method described here could be used to rank order acyl glucuronide forming discovery compounds based on the potential reactivity of the conjugates and their routes of decomposition under physiological conditions. Furthermore, we have shown that in vitro systems such as liver microsomal preparations can be used to generate sufficient quantities of acyl glucuronides from early discovery compounds for NMR characterization. This is particularly important, as we often have limited supply of early discovery compounds to conduct in vivo studies to generate sufficient quantities of acyl glucuronides for further characterization.
authors.affiliation: Pfizer, Pharmacokinetics, Dynamics and Metabolism, Ann Arbor, Michigan 48015, USA. gregory.s.walker@pfizer.com
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Walker
authors.forename: James
authors.initials: J
authors.lastname: Atherton
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bauman
authors.forename: Christopher
authors.initials: C
authors.lastname: Kohl
authors.forename: Wing
authors.initials: W
authors.lastname: Lam
authors.forename: Michael
authors.initials: M
authors.lastname: Reily
authors.forename: Zhen
authors.initials: Z
authors.lastname: Lou
authors.forename: Abdul
authors.initials: A
authors.lastname: Mutlib
mesh_terms: D000215:Acylation; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D001646:Bile / Q000737:chemistry / Q000378:metabolism; D002853:Chromatography, Liquid; D016861:Cyclooxygenase Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D004008:Diclofenac / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D004355:Drug Stability; D005439:Flufenamic Acid / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D020719:Glucuronides / Q000737:chemistry* / Q000378:metabolism* / Q000493:pharmacokinetics; D006207:Half-Life; D007052:Ibuprofen / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D007213:Indomethacin / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D013058:Mass Spectrometry; D008528:Mefenamic Acid / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D015394:Molecular Structure; D051381:Rats; D017207:Rats, Sprague-Dawley; D013237:Stereoisomerism; D013678:Technology, Pharmaceutical / Q000379:methods; D014046:Tolmetin / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D016861:Cyclooxygenase Inhibitors; D020719:Glucuronides; D004008:Diclofenac; D008528:Mefenamic Acid; D005439:Flufenamic Acid; C020549:zomepirac; D014046:Tolmetin; D007052:Ibuprofen; D007213:Indomethacin