A13 Which of the following statements regarding the use of
antifibrinolytic agents is FALSE?
a. Tranexamic acid is a competitive inhibitor of plasminogen and
plasmin.
b. Aprotinin significantly reduces blood loss and transfusion
requirements in cardiac surgery.
c. Use of antifibrinolytics in trauma is supported by several high quality
randomised controlled trials.
d. Arterial and venous thrombosis are uncommon complications of
tranexamic acid use.
e. The risk of anaphylaxis with aprotinin is 0.5%.


A13 C

• Tranexamic acid (TXA) is a competitive inhibitor of plasmin and plasminogen, while aprotinin forms irreversible complexes with a variety of proteases including plasmin. 
• While TXA is synthetic, aprotinin is isolated from bovine lungs and has a high incidence of anaphylaxis (0.5%). 
• A strong evidence base supports the use of antifibrinolytic agents in cardiac surgery, where they have been shown to reduce the requirement for blood transfusion by about 30%. A Cochrane review 1 failed to demonstrate any increased incidence of thrombosis with antifibrinolytics, although a recent study 2 suggested that aprotinin is associated with an increased incidence of myocardial infarction, stroke and renal failure, leading to its withdrawal in the USA. 
• The rationale for use in trauma is extrapolated from evidence in elective cardiac surgery; the ongoing CRASH (Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage) II trial should help determine whether they are effective in this context.