[New thrombolytic agents]

Tissue Plasminogen Activator (t-PA), Single Chain Urokinase Plasminogen Activator or pro-Urokinase (scu-PA or pro-UK) and acyl enzymes are new thrombolytic agents, characterized by a high fibrin affinity, so that they provoke only mild systemic fibrinolytic effect. Their infusion would allie good thrombolytic activity and reduced hemorragic risks, usually related to fibrinogen and others coagulation factors degradation t-PA and scu-PA are natural, physiological substances, obtained by recombinant DNA technology. t-PA infusion in acute myocardial infusion (AMI) has been shown to be at least as efficient than intracoronary Streptokinase (SK) administration, but fibrinogenolysis was much lower as compared to SK. In vitro studies have shown that scu-PA was an efficient thrombolytic agent and has a relative fibrin specificity, at least as similar to t-PA, but much superior to classical Urokinase. The acyl-enzyme APSAC or Eminase is a SK-plasminogen complex in which the proteolytic site has been inactivated with an anisoic-acid. This acyl enzyme has a longer half-life than t-PA and scu-PA, and can be injected as a bolus. Its administration in AMI have shown that APSAC is as effective as SK, but can also provoke severe fibrinogenolysis. These 3 agents seem to have similar thrombolytic activities on coronary thrombi. However, further studies are required to evaluate the bleeding incidence and coronary reocclusion rates associated with their utilisation.