Napsagatran hydrate is a novel and specific inhibitor of thrombin.

Napsagatran causes 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 the compound from the cells into the medium is measured [1][2].

Statistical analysis confirms that thrombus growth in the placebo and AP-1 treated rabbits is not different. In contrast, the reduction of 125I-fibrinogen incorporation by Napsagatran is statistically different from the placebo group (P<0.01). 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.[3].