Thrombolytic agents, capable of dissolving fresh thrombi or emboli, are usually activators of plasminogen (profibrinolysin), plasmin (fibrinolysin), or plasmin-activator mixtures. Streptokinase, urokinase, and other plasminogen activators have been used as thrombolytic agents with encouraging results. The question whether plasmin or a plasminogen activator is the better thrombolytic agent may be answered when preparations of greater purity are tested. Accurate methods for standardizing these drugs have not yet been devised. While commercially available thrombolytic agents have been used in thrombophlebitis and other thromboembolic disorders with seemingly good results, further experimental and clinical evaluation is needed to determine the therapeutic usefulness of these agents.
Brinkhous KM, Roberts HR. Thrombolysis and Thrombolytic AgentsA Brief Review. JAMA. 1961;175(4):284–289. doi:10.1001/jama.1961.03040040016003