Fig. 2.

Thrombin enables thrombus formation by activating multiple coagulation factors, catalyzing the conversion of fibrinogen to fibrin, and causing platelet aggregation. Dabigatran binds at the active site, thus inhibiting both free and fibrin-bound thrombin. Heparin exerts its action by increasing the affinity of antithrombin for thrombin. Heparin can only inhibit free thrombin since fibrin-bound thrombin has both exosites occupied and is relatively protected from the effects of antithrombin