Influence of Cytochrome P450 2C19 on the pharmacokinetics of lansoprazole administered by single and successive intravenous infusion in healthy Chinese volunteers

This study aimed to explore the effect of CYP2C19 polymorphisms on the pharmacokinetics of lansoprazole administered by single and successive intravenous (iv) infusions in healthy Chinese volunteers. A total of 30 subjects, including 20 extensive metabolizers (EMs) and 10 poor metabolizers (PMs) were recruited and randomly assigned to three groups receiving doses of 15, 30 and 60 mg. All subjects received a single dose of lansoprazole during a 60-min period, and only the 30 mg dose group continued to receive the same dose iv for the next seven days (twice daily). Plasma concentrations of lansoprazole were monitored by high performance liquid chromatography (HPLC) at the following times: 15, 30, 45, 60, 75, 105, 165, 225, 300, 390, 480, 600 and 720 min after lansoprazole administration. After a single intravenous infusion in the three groups, AUC, Cmax and t were significantly higher in PMs than in EMs, while total clearance (Cltotal) in PMs was significantly lower than that in EMs. Mean AUC and Cmax ratios in EMs and PMs were 2.1:1 and 1.4:1, respectively. After repeated doses of 30 mg, the AUC, Cmax, and t increased significantly, while the Cltotal decreased significantly in EMs. Mean AUC and Cmax ratios in EMs and PMs amounted to 2.2:1.4 and 1.5:1.2, respectively. Lansoprazole displays a linear increase in AUC and Cmax over a dose range of 15-60 mg, and these were dependent on individual CYP2C19 status.