Evaluation of the Potential for Drug-Induced Liver Injury Based on in Vitro Covalent Binding to Human Liver Proteins

Abstract

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.

Predictability of Idiosyncratic Drug Toxicity Risk for Carboxylic Acid-Containing Drugs Based on the Chemical Stability of Acyl Glucuronide

“…It is reported that the occurrence of IDT is related to clinical doses (Nakayama et al, 2009;Usui et al, 2009) and that IDT is rare with drugs at daily doses of 10 mg or less (Uetrecht, 1999). Therefore, we used the maximum daily dose in the analysis to distinguish the warning drugs from the withdrawn drugs.…”

The chemical, genetic and immunological basis of idiosyncratic drug–induced liver injury

“…Additionally, the quantity of covalent binding in some studies does not show a direct correlation with the incidence of iDILI. 29 The multiple determinant hypothesis suggests that iDILI is dependent on the build-up of many different factors that increase the probability of an adverse event. 30 Whilst CRM formation and covalent binding are some of these factors, they may also be part of a series of events that lead to immune activation.…”

Highlight report: towards the replacement of in vivo repeated dose systemic toxicity testing

“…It may take several weeks to months and repeated doses over a longer period until immune cells have proliferated and matured sufficiently in order to induce a clinically evident DILI. Recently, evidence has been presented that even complex mechanisms requiring repeated doses and interaction of several cell types may be predicted by relatively simple in vitro systems: considering both, protein binding of compounds to liver proteins and the daily dose of drugs allows a good differentiation between DILI inducing and negative compounds (Usui et al 2009;Nakayama et al 2009). Using this approach, the positive DILI compounds acetaminophen, alpidem, bromfenac, carbamazepine, diclofenac, flutamide, imipramine, nefazodone, tacrine, ticlopidine, tienilic acid, and troglitazone could be differentiated from negative compounds acetylsalicylic acid, caffeine, dexamethasone, losartan, ibuprofen, paroxetine, pioglitazone, rosiglitazone, sertraline, theophylline, venlafaxine, and zolpidem (Usui et al 2009).…”