Anticoagulant and antithrombotic action of novel specific inhibitors of thrombin

A series of new specific inhibitors of thrombin, cyclic amides of N alpha-arylsulfonyl-amidinophenylalanine, was studied for anticoagulant action in vitro and in vivo. The inhibitors showed strong anticoagulant effects in vitro. The time course of the anticoagulant effect of the inhibitors in rabbits and rats was monitored using plasma thrombin time determinations. In rats, the inhibitors prevented the formation of experimental venous thrombi and of thrombin-induced microthrombosis. The new derivatives of benzamidine presented may be useful as immediately acting anticoagulants.