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Purpose: Pyrotinib (PTN) is primarily metabolized by cytochrome P450 (CYP)3A4 isozyme. Rifampicin (RIF) is a strong CYP3A4 inducer. Thus, the effect of oral RIF on PTN pharmacokinetics (PK) was evaluated to provide dose recommendation when co-administered.Method: This phase I, open-label study investigated the effects of steady-state RIF administration on single-dose PK of PTN, in 18 healthy participants who received PTN 400 mg single doses on days 1 and 13, and were administrated with RIF 600 mg qd on days 6-16. Each dose for RIF was administrated on an empty stomach, PTN were administrated orally in the morning 30 min after the start of the standard meal. Serial PK samples for PTN were collected on day 1 and day 13. Plasma PTN PK parameters were determined with non-compartmental analysis. Geometric least-squares mean ratios (GMRs) and 90% confidence intervals (CIs) were generated by the mixed-effected model for within-subject treatment comparisons. Safety assessments were performed throughout the study.Results: Eighteen subjects were enrolled and 15 completed the study. RIF significantly reduced PTN exposure: GMRs (90 % CI) for PTN + RIF versus PTN alone were 0.04 (0.034,0.049), 0.04 (0.037,0.054), and 0.11 (0.09,0.124) for area under the curve from time zero to time of last quantifiable concentration (AUC0-t), area under the curve from time zero to infinity (AUC0-∞ ), and maximum observed plasma concentration(Cmax), respectively. PTN alone and co-administered with RIF was well tolerated.Conclusion: Concurrent administration of PTN and RIF was associated with significantly decreased systemic exposure to PTN. The findings suggest that concomitant strong CYP3A4 inducers should be avoided during PTN treatment. Concurrent administration of PTN and RIF was well tolerated.

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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, AUC and AUC 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.