Antifibrinolytics are a class of medication that are inhibitors of fibrinolysis. Examples include aminocaproic acid (ε-aminocaproic acid) and tranexamic acid. These lysine-like drugs interfere with the formation of the fibrinolytic enzyme plasmin from its precursor plasminogen by plasminogen activators (primarily t-PA and u-PA) which takes place mainly in lysine rich areas on the surface of fibrin. These drugs block the binding sites of the enzymes or plasminogen respectively and thus stop plasmin formation.
They are used in menorrhagia and bleeding tendency due to various causes. Their application may be beneficial in patients with hyperfibrinolysis because they arrest bleeding rapidly if the other components of the haemostatic system are not severely affected. This may help to avoid the use of blood products such as fresh frozen plasma (FFP) with its associated risks of infections or anaphylactic reactions.
The indication for use of antifibrinolytic drugs is made with various methods. The most rapid and suitable one is thromboelastometry (TEM) in whole blood, which is even possible in patients on heparin. With various assays, an enhanced fibrinolysis becomes visible in the curve signature (TEMogram) and from the calculated values, e.g. the maximum lysis parameter. A special test for the identification of increased fibrinolysis (APTEM) compares the TEM in the absence or presence of the fibrinolysis inhibitor aprotinin. In severe cases of activated fibrinolysis, this assay confirms the syndrome already in less than 15 min during the early phases of clot formation