Napsagatran hydrate is a novel and specific thrombin inhibitor.
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[1]. The decreasing intracellular amount and efflux of compound from the cells into the medium is measured. The measured CLint,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[2].
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 125I-fibrinogen incorporation by Napsagatran is statistical different from the placebo group (P<0.01)[3].
[1]. Pratico D, et al. Interaction of a thrombin inhibitor and a platelet GP IIb/IIIa antagonist in vivo: evidence thatthrombin mediates platelet aggregation and subsequent thromboxane A2 formation during coronary thrombolysis. J Pharmacol Exp Ther. 1997 Jun;281(3):1178-85. [2]. Lundquist P, et al. Prediction of in vivo rat biliary drug clearance from an in vitro hepatocyte efflux model. Drug Metab Dispos. 2014 Mar;42(3):459-68. [3]. Himber J, et al. Inhibition of tissue factor limits the growth of venous thrombus in the rabbit. J Thromb Haemost. 2003 May;1(5):889-95.