Abstract
CONTEXT: Poziotinib and vonoprazan are two drugs mainly metabolized by CYP3A4. However, the drug-drug interaction between them is unknown. OBJECTIVE: To study the interaction mechanism and pharmacokinetics of poziotinib on vonoprazan. MATERIALS AND METHODS: In vitro experiments were performed with rat liver microsomes (RLMs) and the contents of vonoprazan and its metabolite were then determined with UPLC-MS/MS after incubation of RLMs with vonoprazan and gradient concentrations of poziotinib. For the in vivo experiment, rats in the poziotinib treated group were given 5 mg/kg poziotinib by gavage once daily for 7 days, and the control group was only given 0.5% CMC-Na. On Day 8, tail venous blood was collected at different time points after the gavage administration of 10 mg/kg vonoprazan, and used for the quantification of vonoprazan and its metabolite. DAS and SPSS software were used for the pharmacokinetic and statistical analyses. RESULTS: In vitro experimental data indicated that poziotinib inhibited the metabolism of vonoprazan (IC(50) = 10.6 μM) in a mixed model of noncompetitive and uncompetitive inhibition. The inhibitory constant K(i) was 0.574 μM and the binding constant αK(i) was 2.77 μM. In vivo experiments revealed that the AUC((0-)(T)()) (15.05 vs. 90.95 μg/mL·h) and AUC((0-∞)) (15.05 vs. 91.99 μg/mL·h) of vonoprazan increased significantly with poziotinib pretreatment. The MRT((0-∞)) of vonoprazan increased from 2.29 to 5.51 h, while the CLz/F value decreased from 162.67 to 25.84 L/kg·h after pretreatment with poziotinib. CONCLUSIONS: Poziotinib could significantly inhibit the metabolism of vonoprazan and more care may be taken when co-administered in the clinic.