Clinical pharmacology of tranexamic acid.

Tranexamic acid (AMCA) is a potent antifibrinolytic drug occurring in two isomeric forms; the antifibrinolytic potency resides in the transisomeric form. The main action of AMCA is blocking of the lysine-binding sites of the plasminogen molecule, which are of importance for the binding to fibrin. This prevents activation of plasminogen by plasminogen activator also absorbed to fibrin. AMCA can be administered perorally or intravenously and is excreted into the urine. It enters tissues and fluids in various concentrations and crosses the placenta. There is no evidence of a thrombogenic effect of AMCA, but in accordance with its action, it prolongs dissolution of fibrin deposits already formed. AMCA is a drug of high clinical value for the treatment of bleedings due to both systemic and local fibrinolysis.