- Anticoagulants do not by themselves reduce the size of clots; rather, they prevent further extension of thromboses and allow physiological mechanisms to slowly eliminate the clot burden. However, in certain contexts such as myocardial infarctions and cerebrovascular accidents acute elimination of the clot is necessary to prevent rapidly progressive ischemic injury to critical anatomic regions such as the heart and brain. In such cases, "Thrombolytics" are used, a class of drugs that promote disruption thromboses by triggering direct enzymatic break down coagulated fibrin.
- Thrombolytics ultimately function by directly or indirectly catalyzing the conversion of the inactive proenzyme plasminogen to activated plasmin, an endogenous enzyme which directly cleaves fibrin. By promoting the generation of plasmin, thrombolytics can rapidly accelerate the breakdown of clots.
- Alteplase: Formerly named tissue-Plasminogen Activator (tPA)