Aprotinin acts as an inhibitor of human trypsin, plasmin and plasma and tissue kallikreins, by forming reversible enzyme-inhibitor complexes. Haemostasis is thus re-established by the inactivation of free plasmin. Antifibrinolytics have been shown to reduce bleeding in cardiac surgery following cardiopulmonary bypass.
Antifibrinolytics (e.g. Tranexamic acid) may be useful in bleeding involving mucosal surfaces, such as in dental surgery (particularly in patients with haemophilia and von Willebrand's disease), with excessive menstrual bleeding and with thrombocytopenia or platelet dysfunction. Antifibrinolytics are also sometimes given before certain operations associated with a high risk of serious bleeding. They may also have a platelet-sparing role in patients undergoing liver transplantation or cardiac surgery.
Risks associated with the use of antifibrinolytics
Antifibrinolytics can cause side-effects of nausea, vomiting and diarrhoea. Aprotinin may cause allergic reactions and localised thrombophlebitis. Antifibrinolytics are contraindicated in renal tract bleeding because of the risk of ureteric obstruction and colic.