Effect of linagliptin on the pharmacokinetics and pharmacodynamics of warfarin in healthy volunteers

To investigate the effect of the estimated highest therapeutic dose of linagliptin (5 mg) on the pharmacokinetics and pharmacodynamics of warfarin, a CYP2C9 substrate. This open-label, 2-period, fixed-sequence trial enrolled 18 healthy male volunteers, 17 of whom were homozygous for CYP2C9*1/*1. Subjects received a single oral dose of warfarin (10 mg) followed by a washout period of at least 14 days. Subjects then received oral linagliptin 5 mg once daily for 12 days (i.e. steady state) with a single dose of warfarin (10 mg) on Day 6. R(+) warfarin, S(-) warfarin, prothrombin time (PT) and international normalized ratio (INR) were assayed pre-dose and up to 168 h post-dose. The geometric mean ratios (GMRs) (90% confidence interval (CI)) of AUC0-∞ and Cmax for (linagliptin + warfarin)/warfarin were 98.5 (95.7 - 101.5) and 99.7 (94.7 - 104.9), respectively, for R-warfarin; 103.0 (99.1 - 107.0) and 100.9 (93.7 - 108.6), respectively, for S-warfarin. Concomitant administration of linagliptin and warfarin had o clinically relevant effect on the AUC0-168 for INR or PT. The GMRs (90% CI) of INR nd PT AUC0-168 for (linagliptin + warfarin)/ warfarin were 93.4 (86.2 - 101.1) and 103.2 (95.4 - 111.6), respectively. The corresponding Eax values for both INR and PT were slightly increased after co-administration of linagliptin and warfarin compared with warfarin alone, being 104.3 (85.2 - 127.6) and 15.1 (94.3 -140.6), respectively, reflecting the higher variability of these endpoints. Co-administration of linagliptin and warfarin was well tolerated. Coadministration of linagliptin did not alter the pharmacokinetics or pharmacodynamics of R- or S-warfarin, indicating that no dosage adjustment for warfarin is necessary when co-administered with linagliptin.