Multicenter dose-finding trial for thrombolysis with urokinase preactivated pro-urokinase (TCL 598) in acute myocardial infarction. German Preactivated Pro-Urokinase Study Group.

In a multicenter dose-finding study, the thrombolytic potency of urokinase preactivated pro-urokinase was evaluated. Sixty-two patients were randomly assigned to receive 250,000 U of urokinase plus either 4.5 mega U (group I: n = 33) or 6.5 mega U (group II: n = 29) of pro-urokinase. Patency rates were 36.4% (20.4-54.9%) vs. 54.5% (36.3-71.9%) (n = 27) at 60 minutes and 55.6% (32.5-70.6%) vs. 62.1% (42.3-79.3%) at 90 min into thrombolysis (n.s.). In a third group of 12 patients treated with 500,000 U of urokinase plus 6.5 mega U of pro-urokinase patency was achieved in 33.3% (9.9-65.1%) and 41.7% (15.2-72.3%) at 60 and 90 min, respectively. Patency rates at 24 hr follow-up angiography (n = 35) were 78.6% (49.2-95.3%), 85.7% (57.2-98.2%), and 85.7% (42.1-99.6%). Coagulation analysis in 37 patients revealed similar alterations in the three treatment groups with minor decreases in fibrinogen levels, moderate drops in plasminogen and alpha-2-antiplasmin levels, and moderate increases in the concentrations of the total fibrinogen/fibrin degradation products, the differences between the groups not being significant. Bleeding complications were observed in 12.9%, 13.8%, and 25% of patients in groups I, II, and III, respectively, mainly related to catheter sites. Hence, the safety profile of urokinase preactivated pro-urokinase seems comparable to other thrombolytic regimens. Reopening of occluded coronary arteries, however, is achieved relatively slowly. Thus, in its use for thrombolysis in myocardial infarction, urokinase preactivated pro-urokinase does not seem to offer superior advantages.