What is the mechanism of action for urokinase in thrombolytic therapy?

Updated: Aug 04, 2021
  • Author: Wanda L Rivera-Bou, MD, FAAEM, FACEP; Chief Editor: Erik D Schraga, MD  more...
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Urokinase [10] is the fibrinolytic agent that is most familiar to interventional radiologists and that has been used most often for peripheral intravascular thrombus and occluded catheters.

Urokinase is a physiologic thrombolytic agent that is produced in renal parenchymal cells. Unlike streptokinase, urokinase directly cleaves plasminogen to produce plasmin. When it is purified from human urine, approximately 1500 L of urine is needed to yield enough urokinase to treat a single patient. Urokinase is also commercially available in a form produced by tissue culture, and recombinant DNA techniques have been developed for urokinase production in E coli cultures.

Urokinase was withheld from the market for some years because of manufacturer issues with the FDA but has since been reintroduced. The package insert was revised and now carries indications only for massive PE and PE accompanied by unstable hemodynamics. During the period when urokinase was not available, the FDA encouraged the off-label use of reteplase and alteplase for local-regional lysis of venous and arterial thrombus at any location. Currently, urokinase is readily used for this purpose in different clinical and interventional settings.

In plasma, urokinase has a half-life of approximately 20 minutes. Allergic reactions are rare, and the agent can be administered repeatedly without antigenic problems.

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