Urokinase can directly act on the endogenous fibrinolytic system and 
catalyze the lysis of plasminogen into fibrinolytic enzyme. Plasminolytic enzyme 
can not only degrade fibrinogen clots, but also degrade fibrinogen, coagulation 
factor 5 and coagulation factor 8 in blood circulation, so as to play the role 
of thrombolysis.

  What is the role of urokinase?
  Secondly, urokinase has a fast and good effect on newly formed thrombosis. 
Urokinase can also improve vascular ADP enzyme activity, inhibit ADP-induced 
platelet aggregation and prevent thrombosis.
  Urokinase in patients with intravenous drip, fibrinolytic enzyme activity 
increased significantly in the body, to a few hours after stopping drug, 
fibrinolytic enzyme activity to restore the original level, but plasma, fibrin 
and fibrinogen level is reduced, and the increase of their degradation products 
can last 12 to 24 hours, the thrombolytic effect of urokinase and drug dosage, 
dosing time window has obvious relevance.