Effects of CYP3A4 variants and drug–drug interactions on the metabolism of fexinidazole

Fexinidazole is a ctirical treatment for Human African trypanosomiasis in Africa, but its metabolic characteristics are not fully understood. This study investigated the impacts of CYP3A4 genetic polymorphisms and (−)-epigallocatechin gallate (EGCG) on the metabolism of fexinidazole in vitro (rat liver microsomes (RLM), human liver mircosomes (HLM), and nine CYP3A4 variants) and in vivo (rat) models. Ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was utilized to quantify fexinidazole and its metabolites. The results showed that fexinidazole was metabolized mainly by CYP3A4, which was significantly modulated by CYP3A4 polymorphisms. In addition, EGCG significantly inhibited the metabolism of fexinidazole in both RLM (IC 50  = 8.02 ± 0.28 μM) and HLM (IC 50  = 9.97 ± 0.43 μM) via mixed-type inhibition mechanisms. In vivo , co-administration of EGCG significantly altered the pharmacokinetic parameters of fexinidazole, increasing the AUC and C max by approximately 1.46 and 1.44-fold, respectively, while decreasing clearance (CL z/F ). Furthermore, continuous administration of EGCG significantly downregulated key hepatic CYP450 (CYP3a1, CYP2d1/2, CYP2b1/2, and CYP2c11) at both the protein and mRNA levels. This study elucidated the major metabolic pathways of fexinidazole and reported the effects of genetic polymorphisms and the drug EGCG on its metabolism for the first time.