There is a considerable difference between the mechanism of action of the lysine analogues, tranexamic acid and epsilon-aminocaproic acid, and the serine protease inhibitor aprotinin. Aprotinin acts to inactivate free plasmin, but with little effect on bound plasmin, whereas the lysine analogues are designed to prevent excessive plasmin formation by fitting into plasminogen's lysine-binding site to prevent the binding of plasminogen to fibrin. Aprotinin is associated with a reduction in bleeding and transfusion requirements following major surgery, and has a dose-response profile, compared with no dose-response effect in the one study investigating tranexamic acid in cardiac surgical patients. Following its withdrawal in 2007, which is explained in detail in this review, the regulators have now licensed aprotinin for myocardial revascularisation only, which is relatively low-risk for bleeding.
© 2014 The Association of Anaesthetists of Great Britain and Ireland.