title: Evaluation of the potential for drug-induced liver injury based on in vitro covalent binding to human liver proteins.
abstract: Prediction of idiosyncratic drug-induced liver injury (DILI) is difficult, and the underlying mechanisms are not fully understood. However, many drugs causing DILI are considered to form reactive metabolites and covalently bind to cellular macromolecules in the liver. The objective of this study was to clarify whether the risk of idiosyncratic DILI can be estimated by comparing in vitro covalent binding (CB) levels among 12 positive compounds (acetaminophen, alpidem, bromfenac, carbamazepine, diclofenac, flutamide, imipramine, nefazodone, tacrine, ticlopidine, tienilic acid, and troglitazone) for DILI and 12 negative compounds (acetylsalicylic acid, caffeine, dexamethasone, losartan, ibuprofen, paroxetine, pioglitazone, rosiglitazone, sertraline, theophylline, venlafaxine, and zolpidem). After incubation with human liver microsomes in the presence of NADPH, there was a large overlap in the distribution of CB amounts between the positive and negative groups. On addition of UDP-glucuronic acid (UDPGA) as a cofactor for glucuronidation, the CB levels of bromfenac and diclofenac were increased. With addition of nucleophilic glutathione (GSH), values for most compounds were decreased. However, separation of the two groups on the basis of CB could not be improved by UDPGA or GSH. Furthermore, CB with human hepatocytes also failed to discriminate positive from negative compounds. Therefore, the CB amount alone is not sufficient for risk assessment of DILI. In contrast, when the CB amount was multiplied by the maximum daily dose, which may reflect maximum hepatic exposure, the two groups did become discriminated. Taken together, our findings suggest that the combination of CB amount and daily dose can estimate the risk of idiosyncratic DILI.
authors.affiliation: Pharmacokinetics Research Laboratories, Dainippon Sumitomo Pharma Co., Ltd., Kasugade-naka, Konohana-ku, Osaka 554-0022, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Usui
authors.forename: Masashi
authors.initials: M
authors.lastname: Mise
authors.forename: Takanori
authors.initials: T
authors.lastname: Hashizume
authors.forename: Masashi
authors.initials: M
authors.lastname: Yabuki
authors.forename: Setsuko
authors.initials: S
authors.lastname: Komuro
mesh_terms: D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology* / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D020723:Glucuronic Acid / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D055432:Metabolomics; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D011485:Protein Binding; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors
chemical_list: D009249:NADP; D020723:Glucuronic Acid; D003577:Cytochrome P-450 Enzyme System; D014453:Glucuronosyltransferase; D005978:Glutathione