Effects of tranexamic acid on fibrinolysis, fibrinogenolysis and amidolysis.

When Glu-plasminogen (Glu-plg) was activated by urokinase (UK) in the presence of fibrinogen or fibrinogen plus tranexamic acid (1 mM), or else tranexamic acid (1 mM), the activation as measured by the hydrolysis of S-2251 was enhanced by tranexamic acid or fibrinogen or both. When plasma or clotted plasma was activated by UK in the presence of 1 mM tranexamic acid, fibrinolysis was completely inhibited. When Lys-plg was activated by UK in the presence of tranexamic acid and fibrin or fibrinogen, fibrinolysis was completely inhibited by 1 mM tranexamic acid, but some inhibition of fibrinogenolysis was observed. The release of B beta 15-42 from fibrin in clotted plasma activated by UK was inhibited to some extent by 1 mM tranexamic acid. The release of B beta 15-42 from fibrin after UK-activation of Lys-plg was partly inhibited by tranexamic acid. In conclusion, tranexamic acid in the concentration of 1 mM enhanced amidolysis, but inhibted fibrinolysis measured by the generation of fibrin-degradation products. Fibrinogenolysis and the release of B beta 15-42 from fibrin were partly inhibited.