Fibrinolytic mechanism, biochemistry, and preclinical pharmacology of recombinant prourokinase.
The purpose of this review is to provide a biochemical characterization of recombinant prourokinase (r-ProUK [ABT-187]), including a description of its clot-specific fibrinolytic mechanism. In addition, the preclinical data will be briefly reviewed, demonstrating the efficacy of r-ProUK as a potent therapeutic plasminogen activator. r-ProUK was purified to homogeneity from the culture medium of SP2/0 mouse hybridoma cells. The fibrinolytic potency of r-ProUK was characterized by both in vitro clot lysis experiments in human plasma and a canine femoral artery thrombosis model. In the in vitro clot lysis system, with use of clots prepared from fresh frozen human plasma, r-ProUK exhibits a lag phase to the onset of lysis and a concentration-dependent threshold effect due to the presence of the inhibitors alpha 2-antiplasmin and plasminogen activator inhibitor (PAI-1). Effective clot lysis can be achieved without degradation of the fibrinogen in the surrounding plasma. Over a dose range of 50,000-220,000 IU, the canine femoral artery thrombosis model shows a dose-dependent relationship for r-ProUK and effective clot lysis. The lytic activity of r-ProUK is significantly enhanced in this model by the concomitant administration of heparin as an adjunctive agent for thrombolytic treatment. Fibrinogen, plasminogen, and alpha 2-antiplasmin levels in the systemic circulation were unaltered during the 30-minute infusion period and a 4-hour observation period, in which 85% lysis was achieved with r-ProUK (100,000 IU) and heparin. Moreover, restoration of blood flow in the previously fully occluded femoral artery was achieved within minutes of the start of the r-ProUK infusion. The experimental findings presented here are consistent with the clot-specific fibrinolytic mechanism of r-ProUK. Effective clot lysis can be achieved without alteration of the systemic coagulation and fibrinolytic parameters.
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Pharmaceutical Products Division, Abbott Laboratories, Abbott Park, Ill 60064-3500, USA.
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D000595:Amino Acid Sequence; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005342:Fibrinolysis / Q000187:drug effects*; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology*; D015912:Thrombolytic Therapy; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000494:pharmacology*
D005343:Fibrinolytic Agents; D011994:Recombinant Proteins; D014568:Urokinase-Type Plasminogen Activator; C067551:saruplase