Tranexamic Acid

choi

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Art Chimes, Cheap Drug Could Cut Accident Deaths Dramatically, Study Finds; Clotting medicine has potential to save tens of thousands from bleeding to death. VOA, June 17, 2010.
http://www1.voanews.com/english/news/health/Cheap-Drug-Could-Cut-Accident-Deaths-Dramatically-Study-Finds-96562574.html

My comment:
(1) The Chinese translation of this VOA report:

柴姆斯, 能挽救生命的廉价药物. VOA Chinese, July 1, 2010.
http://www1.voanews.com/chinese/news/health/20100701-HEALTH-BRIEF-97618504.html

(2) The publication on which the VOA report was based:

CRASH-2 Trial Collaborators, Effects of tranexamic acid on death, vascular occlusive events, and blood transfusion in trauma patients with significant haemorrhage (CRASH-2): a randomised, placebo-controlled trial. The Lancet vol __: Pages __ (June 15, 2010, online publication date)
http://download.thelancet.com/flatcontentassets/pdfs/S0140673610608355.pdf

(a) What does CRASH-2 stand for?

Sentence 1 under Methods: "CRASH-2 (Clinical Randomisation of an
Antifibrinolytic in Significant Haemorrhage 2) is a large placebo controlled trial of the effects of early administration of a short course of tranexamic acid on death, vascular occlusive events, and the receipt of blood transfusion.

(b) What is mechanism of Tranexamic acid (TXA)?

"Introduction" in the Lancet article states, "Tranexamic acid is a synthetic derivative of the aminoacid lysine that inhibits fibrinolysis by blocking the lysine binding sites on plasminogen."

(i) Fibrin is polymerized to make a blood clot. Fibrin is a peptide made up of amino acids, including lysine. A very small amount of naturally occurring plasmin cleaves fibrin at carboxyl end of lysine, to which plasminogen is attached and converted to plasmin to eventually dissolve the blood clot.

(ii) Lysine has a chemical structure NH2-(CH2)4-CH(NH2)-COOH.

TXA has (NH2) removed and (CH2)2 added and a ring completed.
http://en.wikipedia.org/wiki/Tranexamic_acid
This synthetic lysine analog interferes with plasminogen. That is what the Introduction means.

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