Contribution of Major Metabolites toward Complex Drug-Drug Interactions of Deleobuvir: In Vitro Predictions and In Vivo Outcomes

Abstract

The drug-drug interaction (DDI) potential of deleobuvir, an hepatitis C virus (HCV) polymerase inhibitor, and its two major metabolites, CD 6168 (formed via reduction by gut bacteria) and deleobuvir-acyl glucuronide (AG), was assessed in vitro. Area-under-the-curve (AUC) ratios (AUCi/AUC) were predicted using a static model and compared with actual AUC ratios for probe substrates in a P450 cocktail of caffeine (CYP1A2), tolbutamide (CYP2C9), and midazolam (CYP3A4), administered before and after 8 days of deleobuvir administration to HCV-infected patients. In vitro studies assessed inhibition, inactivation and induction of P450s. Induction was assessed in a short-incubation (10 hours) hepatocyte assay, validated using positive controls, to circumvent cytotoxicity seen with deleobuvir and its metabolites. Overall, P450 isoforms were differentially affected by deleobuvir and its two metabolites. Of note was more potent CYP2C8 inactivation by deleobuvir-AG than deleobuvir and P450 induction by CD 6168 but not by deleobuvir. The predicted net AUC ratios for probe substrates were 2.92 (CYP1A2), 0.45 (CYP2C9), and 0.97 (CYP3A4) compared with clinically observed ratios of 1.64 (CYP1A2), 0.86 (CYP2C9), and 1.23 (CYP3A4). Predictions of DDI using deleobuvir alone would have significantly over-predicted the DDI potential for CYP3A4 inhibition (AUC ratio of 6.15). Including metabolite data brought the predicted net effect close to the observed DDI. However, the static model over-predicted the induction of CYP2C9 and inhibition/inactivation of CYP1A2. This multiple-perpetrator DDI scenario highlights the application of the static model for predicting complex DDI for CYP3A4 and exemplifies the importance of including key metabolites in an overall DDI assessment.

Role of Cytochrome P450 2C8 in Drug Metabolism and Interactions

“…2 and 5; Table 8; Ogilvie et al, 2006;Tornio et al, 2014). Very recently, also the acyl glucuronide of deleobuvir, an HCV protease inhibitor, was found to be a very potent mechanism-based inhibitor of CYP2C8 (Sane et al 2015). In addition, there is in vitro evidence suggesting that the carbamoyl glucuronide metabolite of Lu AA34893 may affect CYP2C8 in a similar manner (Kazmi et al, 2010).…”

Clopidogrel Markedly Increases Plasma Concentrations of CYP2C8 Substrate Pioglitazone

“…In addition to clopidogrel acyl-b-D-glucuronide, gemfibrozil 1-O-b-glucuronide and deleobuvir acyl glucuronide (M829/2) have been identified as timedependent inhibitors of CYP2C8 (Shitara et al, 2004;Ogilvie et al, 2006;Tornio et al, 2014;Sane et al, 2016). The active site of CYP2C8 is relatively large (Schoch et al, 2004) and can accommodate these glucuronide metabolites, allowing their metabolism to a reactive species that inactivates CYP2C8.…”

Cytochrome P450 and Non-Cytochrome P450 Oxidative Metabolism: Contributions to the Pharmacokinetics, Safety, and Efficacy of Xenobiotics

“…Furthermore, as metabolite contributions to drug-drug interactions have gained importance since the issuance of new regulatory guidances, examples of metabolites formed by non-P450s that can contribute to clinically relevant drug-drug interactions have been identified (VandenBrink and Isoherranen, 2010;Yeung et al, 2011;Yu and Tweedie, 2013). A few classic examples exemplify metabolites formed by non-P450 enzymes in playing a role in inhibiting P450 are gemfibrozil Wang et al, 2002), clopidogrel (Tornio et al, 2014), and, more recently, deleobuvir (Sane et al, 2016), in which UGT-catalyzed acyl glucuronide formation is responsible for inactivating CYP2C8 and resulting in significant drug-drug interactions. Conversely, the addition of a sulfate group to a nucleophilic ligand is catalyzed by sulfotransferases.…”