ATC Group: B02A Antifibrinolytics

Human alpha₁-proteinase inhibitor is understood to be the primary anti-protease in the lower respiratory tract, where it inhibits neutrophil elastase (NE). Normal healthy individuals produce sufficient alpha₁-proteinase inhibitor to control the NE produced by activated neutrophils and are thus able to prevent inappropriate proteolysis of lung tissue by NE.

Aminocaproic acid is 6-aminohexanoic acid, which acts as an inhibitor of fibrinolysis. The fibrinolysis-inhibitory effects of aminocaproic acid appear to be exerted principally via inhibition of plasminogen activators and to a lesser degree through antiplasmin activity.

Aprotinin is a broad spectrum protease inhibitor which has antifibrinolytic properties. By forming reversible stoichiometric enzyme-inhibitor complexes, aprotinin acts as an inhibitor of human trypsin, plasmin, plasma kallikrein and tissue kallikrein, thus inhibiting fibrinolysis.

Tranexamic acid is an antifibrinolytic that competitively inhibits the activation of plasminogen to plasmin. Tranexamic acid is a competitive inhibitor of plasminogen activation, and at much higher concentrations, a noncompetitive inhibitor of plasmin, i.e., actions similar to aminocaproic acid. Tranexamic acid is about 10 times more potent in vitro than aminocaproic acid. Tranexamic acid binds more strongly than aminocaproic acid to both the strong and weak receptor sites of the plasminogen molecule in a ratio corresponding to the difference in potency between the compounds.

Ulinastatin is a serine protease inhibitor that reduces the pro-inflammatory response as a result of sepsis, acute pancreatitis, trauma or surgery. It inhibits coagulation and fibrinolysis and promotes microperfusion. Thus, ulinastatin is an effective agent for immune modulation to prevent organ dysfunction and promote homeostasis.