Plasminogen, a glycoprotein pro-enzyme produced by the liver, is converted into plasmin by tissue plasminogen activator (TPA). The plasminogen molecule is folded into loops called kringles that stick out like fingers. Plasminogen binds to fibrin via lysine-binding sites on the tips of these kringles. If the lysine residues on fibrin are enzymatically removed, the binding of plasminogen is inhibited.
TPA also binds to fibrin thus localizing and enhancing plasmin formation. Plasmin bound to fibrin is also less susceptible to inhibitors. Plasmin splits fibrin into fibrin degradation products. This exposes more lysine residues which bind more plasminogen, thus accelerating fibrinolysis. TXA inhibits fibrinolysis by reducing the binding of plasminogen to fibrin.
Tranexamic acid prevents blood clots from breaking down and reduces bleeding. However, its role in traumatic brain injury remains uncertain. The CRASH-3 trial is a randomised trial that will examine the effect of tranexamic acid (versus placebo) on death and disability in 13,000 patients with traumatic brain injury.
In response to the release of the Woman trial results, the WHO Department of Reproductive Health and Research is working with the Cochrane Pregnancy and Childbirth Group to fast-track the update of the existing Cochrane systematic review on treatment of primary postpartum haemorrhage, with priority given to the use of tranexamic acid for PPH treatment. Once completed, WHO will convene a virtual technical consultation of international experts to review the evidence, and update the existing WHO recommendation on tranexamic acid for PPH treatment as needed.
Nigeria's Health Minister, Professor Isaac Adewole has said that deaths of women due to postpartum haemorrhage (PPH), a severe form of bleeding after childbirth, was a huge problem in Nigeria and that he will promote the use of tranexamic acid to reduce these deaths.
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