Evaluation of gastric pH-dependent drug interaction between famitinib and the commonly used proton pump inhibitor omeprazole in healthy subjects

Aims: To evaluate the potential gastric pH-dependent drug-drug interaction (DDI), safety and tolerability of famitinib co-administered with omeprazole in healthy subjects. Methods: Twenty healthy subjects were enrolled in a single-center, single-arm, open-label, fixed-sequence study. Famitinib was administered as a single oral 25 mg under a fasting condition on day 1, omeprazole (40 mg once daily) was given on days 10–14, concomitantly with famitinib on day 15, and for the follow-up 7 additional days (days 16–22). Blood samples were collected at predetermined timepoints for the pharmacokinetic analysis of both famitinib and its metabolite SHR116637 following each famitinib dose. Safety and tolerability were assessed during the whole progress via clinical laboratory tests. Results: The least-squares geometric mean ratios (GMRs) (90% CI) of C max , AUC 0-t and AUC 0-∞ for famitinib combined with omeprazole to famitinib alone were 0.989 (0.953, 1.027), 0.956 (0.907, 1.007) and 0.953(0.905, 1.005) respectively. For the metabolite SHR116637, their GMRs (90% CI) of the above parameters were 0.851 (0.786, 0.920), 0.890 (0.838, 0.946）and 0.887 (0.835, 0.943), indicating the absence of significant differences in the parameters respectively. During the treatment period, 9(45%) subjects reported 16 treatment emergent adverse events (TEAE), among which 6 subjects (30%) reported 9 TEAEs and 1 subject (5%) reported 1 TEAE during famitinib or omeprazole administered alone respectively, 5 subjects (25.0 %) reported 6 TEAEs during in the combined administration phase. Conclusion: The PPI omeprazole did not have a significant influence on the pharmacokinetics (PK) of famitinib and SHR116637, and the safety profile was good upon co-administration.