Drug-Drug Interaction Study to Assess the Effects of Multiple-Dose Pitavastatin on Steady-State Warfarin in Healthy Adult Volunteers

Abstract

Warfarin, an antagonist of vitamin K, which inhibits clotting factor synthesis, is prescribed for thrombosis prophylaxis and treatment and is known to have a narrow therapeutic range. Pitavastatin is a potent HMG-CoA reductase inhibitor. In this study, the influence of multiple-dose pitavastatin (4 mg once daily) on steady-state warfarin pharmacodynamic and pharmacokinetic profiles was investigated in 24 healthy male participants whose international normalized ratio (INR) was maintained by individualized doses of warfarin. The ratio of the least squares mean of prothrombin time and INR was 0.989 (90% confidence interval [CI], 0.955-1.023) and 0.993 (0.956-1.209), respectively (test: warfarin + pitavastatin; reference: warfarin only). The geometric mean ratios of C(max) and AUC were 1.034 (90% CI, 0.994-1.075) and 1.066 (1.035-1.099), respectively, for R-warfarin and 1.033 (0.995-1.073) and 1.058 (1.026-1.092), respectively, for S-warfarin. Warfarin pharmacodynamic profiles and pharmacokinetic profiles did not differ between the warfarin monotherapy and the coadministration of pitavastatin and warfarin. No drug-drug interaction between pitavastatin and warfarin was demonstrated.