Fundamentals of fibrinolytic therapy.

The fibrinolytic system is activated by the conversion of plasminogen to plasmin by mediators such as tissue extract, plasma factor XII, or the exogenous activators urokinase (UK) and streptokinase (SK). The foreign protein composition of SK is responsible for the allergic response observed in some patients following administration. Clinical and investigational evidence has also shown a higher incidence of hemorrhagic complications with SK compared with UK. In general, thrombolytic therapy is a safe, effective way to resolve thrombotic obstruction in patients with such problems as acute pulmonary embolism, acute myocardial infarction, or occluded intravascular lines.