ROLE OF ALPHA-2-PLASMIN INHIBITOR IN THE APPEARANCE OF FIBRINOLYTIC-ACTIVITY DURING UROKINASE ADMINISTRATION, AND AN EVALUATION OF THE OPTIMAL UROKINASE DOSAGE

Urokinase(UK) was injected into 9 patients with thrombotic diseases at several different doses(2-180×104 IU/day) in order to estimate the minimal dosage that induces fibrinolytic activity in the peripheral blood, and to evaluate the role of α2-plasmin inhibitor(α2PI) in the appearance of fibrinolysis during UK administration. The correlation coefficients between UK/day and α2PI, plasminogen, α1-antitrypsin(α1AT), α2-macroglobulin(α2M) and fibrinogen were -0.75, -0.54, 0.39, -0.37 and -0.17, respectively. Above 50×104 IU of UK/day, the α2PI level fell below 60%, and above 150x104 IU of UK/day it fell below 30%. The correlation coefficients between lysis area on fibrin plates and α2PI, α1AT, α2M, UK/day and plasminogen were -0.69, 0.51, -0.31, 0.30 and -0.26, respectively. When the level of α2PI fell below 60%, lysis was observed on the fibrin plates in 13 of 20 samples(65%), whereas above 60% of α2PI it was observed in only 4 of 35 samples(11%). The correlation coefficients between level of α2PI and plasminogen, α1AT, α2M and fibrinogen were 0.50, -0.48, 0.38 and 0.29, respectively. The above results suggest that a dosage of about 50x104 IU/day of UK should be administered in order to lower the level of α2PI to below 60% and induce a fibrinolytic state in the peripheral blood. © 1979.