Comparison of thrombolytic agents: selected hematologic, vascular and clinical events.
Plasminogen activators of distinct structure and biochemical action seem to be more equivalent than unique regarding induced blood changes and clinical complications. All of the activators ultimately degrade substrate through plasmin, resulting in a striking hypocoagulable state characterized primarily by a decrease in fibrinogen concentration. Infusion regimens are inversely proportional to the half-life of the activator, which is relatively long with anisoylated plasminogen streptokinase activator complex (APSAC), intermediate for streptokinase (SK) and urokinase (UK), and very short for recombinant tissue plasminogen activator (rt-PA) and recombinant single-chain urokinase plasminogen activator (scu-PA). After therapy is discontinued, hypofibrinogenemia persists until activator is cleared from the blood, then is slowly corrected over 48 hours, regardless of which thrombolytic agent has been used. Coagulation and platelet activity may be transiently accentuated soon after administration of the agent. Hypercoagulability contributes to vascular reocclusion, especially when acting in concert with the thrombogenic influences of residual thrombus and the original ruptured atherosclerotic plaque. In the first 3 to 4 hours after symptom onset, coronary artery reperfusion can be achieved with all of the thrombolytic agents in 50 to 60% of patients, with a greater thrombolytic potential of rt-PA over SK in thrombi of greater than 4 hours' duration. After coronary artery reperfusion, reocclusion occurs in 10 to 20% of patients, more often after rt-PA than SK treatment. Antiplatelet agents such as aspirin decrease the incidence of reocclusion and when added to either SK or rt-PA, decrease mortality after acute myocardial infarction by half. APSAC appears to have a maximal beneficial effect in reducing mortality even without aspirin.(ABSTRACT TRUNCATED AT 250 WORDS)
Marder
V J
VJ
Department of Medicine, University of Rochester School of Medicine & Dentistry, New York.
D005343:Fibrinolytic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D009203:Myocardial Infarction / Q000188:drug therapy; D010960:Plasminogen Activators / Q000627:therapeutic use; D014654:Vascular Patency / Q000187:drug effects*
D005343:Fibrinolytic Agents; D010960:Plasminogen Activators