In Vitro Characterization of a Novel Factor Xa Inhibitor, RPR 130737

or gel-filtered platelets were used as the phospholipid source. An FX-deficient plasma clotting-time RPR 130737 inhibited factor Xa (FXa) with a Ki correction assay further demonstrated that RPR of 2.4 nM and also displayed excellent specificity 130737 was a specific inhibitor of FXa. RPR 130737 toward FXa relative to other serine proteases. It showed no effect on platelet aggregation in vitro. showed selectivity of more than 1000-fold over These results indicate that RPR 130737 has the thrombin, activated protein C, plasmin, tissue-plaspotential to be developed as an antithrombotic minogen activator, and trypsin. RPR 130737 proagent based on its potent and selective inhibitory longed plasma activated partial thromboplastin effect against FXa. © 2000 Elsevier Science Ltd. time and prothrombin time in a dose-dependent