Thrombin

Napsagatran (Ro 46-6240), the selective thrombin inhibitor, induces a dose-dependent prolongation of the activated partial thromboplastin time (aPTT) and prothrombin time (PT) that is evident 15 min after administration of the bolus of Napsagatran. Napsagatran also reduces the time to reperfusion in a dose-dependent manner and delays or prevents reocclusion. The decreasing intracellular amount and efflux of compound from the cells into the medium is measured. The measured CL _int,efflux values are 0.13±0.06, 3.2±0.6, 10.1±2.3, and 110±2.8 for Digoxin, Fexofenadine, Napsagatran, and Rosuvastatin, respectively, thus representing drugs with a >800-fold range of efflux rates.

After the first hour of drug administration (from 0 to 60 min), the incorporated radioactivity into thrombi increased from baseline by 73±13, 67±22 and 32±10% in placebo, AP-1 and Napsagatran-treated rabbits, respectively. Statistical analysis confirm that thrombus growth in the placebo and AP-1 treated rabbits is not different. In contrast, reduction of ¹²⁵ I-fibrinogen incorporation by Napsagatran is statistical different from the placebo group (P<0.01).