An Evaluation of the Inhibitory Effect of Apatinib on Ilaprazole Metabolism: in vitro, in vivo and in silico Study

Background Ilaprazole is a novel proton pump inhibitor (PPI) approved orally in China and Korea for the treatment of gastric ulcers, duodenal ulcers (DU) and erosive esophagitis. It is mainly metabolized to ilaprazole sulfone by CYP3A4.Methods The quantitative determination method of ilaprazole and its metabolite ilaprazole sulfone was optimized and fully validated by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). In addition, the effect of apatinib on ilaprazole and its metabolite ilaprazole sulfone was evaluated by in vitro and in vivo experiments using rat liver microsomes (RLM), human liver microsomes (HLM), molecular docking and Sprague-Dawley (SD) rats.Results The results of bioanalytical methodology showed that ilaprazole and ilaprazole sulfone had good linear relationship in plasma samples, and their selectivity, accuracy, precision, stability, matrix effect, recovery, carry-over, dilution integrity and re-injection reproducibility all met the needs of quantitative analysis of samples. In vitro, apatinib inhibited the metabolism of ilaprazole with half-maximum inhibitory concentration (IC50) values of 1.60 and 16.28 μM in RLM and HLM, respectively, and was a mixed inhibitor (non-competitive + competitive) in both systems. In addition, in both systems, the metabolic stability results indicated that apatinib inhibited the metabolism of ilaprazole. In vivo, under the action of apatinib, the AUC(0-t), AUC(0-∞), Cmax of ilaprazole and the AUC(0-t), AUC(0-∞), t1/2, Cmax of its metabolite ilaprazole sulfone were all significantly increased, while the CLz/F of both were significantly decreased. In vitro and in vivo studies showed that apatinib inhibited the metabolism of ilaprazole. Finally, molecular docking was performed as a supportive visualization tool and suggested possible spatial overlap within the CYP3A4 active site.Conclusion In vitro systems and SD rats, apatinib exhibited an inhibitory effect on the metabolism of ilaprazole. In addition, molecular docking provided structural context for the observed interaction. However, whether the same phenomenon exists in humans remains to be further investigated.