Effects of Cytochrome P450 enzymes and drug–drug interaction on donafenib metabolism: in vivo, in vitro and in silico

This study systematically elucidated the metabolic characteristics of the hepatocellular carcinoma (HCC) therapeutic drug donafenib and its drug–drug interaction (DDI) with the antiviral agent arbidol. In vitro phenotyping assays using chemical inhibitors and recombinant CYP enzymes identified CYP3A4 as the primary enzyme catalyzing donafenib N-oxide formation. This was further confirmed by in vivo pharmacokinetic experiments in Cyp3a1/2 knockout rats, where AUC (0-t) , AUC (0-∞) and t 1/2 of donafenib were increased compared with wild-type rats. Additionally, the study was the first to report the effects of 8 CYP3A4 variants (CYP3A4.39-.46) on donafenib metabolism. Among these, 7 variants (except CYP3A4.42) had reduced metabolic catalytic activity compared to wild-type CYP3A4.1, and the intrinsic clearance (CL int ) was 8.60%–97.89% of that of CYP3A4.1. Subsequently, the potential mechanism of enzymatic activity changes was investigated through molecular docking. Finally, the study found that arbidol significantly inhibited donafenib metabolism, where the half-maximum inhibitory concentration (IC 50 ) value of arbidol was 3.16 ± 0.09 μM in rat liver microsome (RLM) and 36.38 ± 1.23 μM in human liver microsome (HLM), respectively. Animal studies have shown that the pharmacokinetics of donafenib were significantly altered following co-administration of arbidol in Sprague-Dawley rats. The results indicated that the AUC (0-t) , AUC (0-∞) and C max of donafenib were increased by 1.19-, 1.05- and 0.54-fold, respectively. Moreover, T max was prolonged by 68.42%, while CL z /F was decreased by 53.85%. These results provided critical references for clinical dosage adjustment, facilitating personalized treatment and reducing the risk of adverse reactions.