Inhibitors, endogenous proteolytic enzymes

So far, the endogenous fibrinolytic enzyme plasmin could not successfully be used in thrombolysis because upon injection, it was immediately blocked by endogenous inhibitors, particularly by (X2-antiplasmin. Plasmin became fibrinolytically effective only after consumption of these inhibitors. To obtain a fibrinolytic effect, large quantities of plasmin were required, which in turn led to hyperplasminemia. This caused proteolytic degradation of fibrinogen and several clotting factors and hence hemordiagic complications. 

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