Question 4

Describe the pharmacology of tranexamic acid.

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College Answer

Tranexamic acid is a drug used to reduce bleeding in trauma or surgery. It is also used for hereditary angioedema and menstrual bleeding. It is being increasingly used in critically ill patients. As a Level B listed drug within the Primary Syllabus candidates would be expected to know it in some depth. Often basic information such as mechanism of action, pharmacokinetics and adverse effects was lacking.


Name Tranexamic acid
Class Serine protease inhibitor
Chemistry Monocarboxylic acid (a synthetic derivative of the amino acid lysine)
Routes of administration IV, nebulised, topical, oral
Absorption 50% absorbed from the GI tract; bioavailability is about 30-35%. Most of it is not metabolised.
Solubility pKa of 10.22; highly water-soluble, but minimally fat-soluble
Distribution VOD = 0.18 L/kg; minimally protein-bound (3%, all of which is accounted for by its binding to plasminogen). After some loading (eg. several doses over 24-36 hrs), enough of it distributes to the tissues to continue having a sustained antifibrinolytic effect for many hours.
Target receptor Plasminogen
Metabolism Minimally metabolised
Elimination 95% of the dose is excreted unchanged in the kidneys; half-life is 2 hours
Time course of action Relatively short-acting, very rapid onset of effect
Mechanism of action Competitive inhibitor of plasminogen activation (by binding to the 5-lysine site on plasminogen). This inhibits the formation of plasmin and displaces plasminogen from the surface of fibrin.
Clinical effects Prevents the breakdown of fibrin, thus maintaining clot integrity. Numerous other effects (as it also inhibits other proteases), as well as indirect effects via plasminogen inhibition (eg. on complement activation, where by reducing plasmin activity it reduces the consumption of C1 esterase inhibitor)
Single best reference for further information Data sheet from


Pilbrant, Å., M. Schannong, and J. Vessman. "Pharmacokinetics and bioavailability of tranexamic acid." European journal of clinical pharmacology 20.1 (1981): 65-72.

Dunn, Christopher J., and Karen L. Goa. "Tranexamic acid." Drugs 57.6 (1999): 1005-1032.

McCormack, Paul L. "Tranexamic acid." Drugs 72.5 (2012): 585-617.

Wellington, Keri, and Antona J. Wagstaff. "Tranexamic acid." Drugs 63.13 (2003): 1417-1433.

Tengborn, Lilian, Margareta Blombäck, and Erik Berntorp. "Tranexamic acid–an old drug still going strong and making a revival." Thrombosis research 135.2 (2015): 231-242.

Griffin, James D., and Leonard Ellman. "Epsilon-aminocaproic acid (EACA).Seminars in thrombosis and hemostasis. Vol. 5. No. 1. 1978.