Tranexamic Acid Pharmacology
Tranexamic acid is an important medicine to treat or prevent blood loss; a drug first discovered in 1962 by the Japanese medical scientist, Utako Okamoto. Since then, the drug has proved valuable in the treatment of a wide range of situations in which patients present with excessive blood loss.
There are many situations in which it becomes necessary to control blood loss. For example, in cases of:
- major trauma
- heavy menstrual bleeding
- hereditary angioedema
Tranexamic acid has also been used to reduce blood loss in patients suffering from severe epistaxis, or nosebleed. Tranexamic acid may also be used for clinical purposes not listed in this guide.
Common brand names of tranexamic acid include Cyklokapron and Lysteda. Tranexamic acid can be administered via the oral route, the intravenous route, and the topical route.
Mechanism of Action
Tranexamic acid is a synthetic analog of the amino acid, lysine.
Mechanistically, tranexamic acid is an antifibrinolytic drug – preventing the breakup of fibrin clots.
It achieves this by binding to lysine receptor sites found on the surface of plasminogen. TXA binding prevents plasminogen from converting into plasmin. This prevents fibrin degradation and decreases the risk of further bleeding.
Common side effects with tranexamic acid include:
- Increased risk of blood clots – such as DTV or PE
- Color vision disturbances
- Allergic reactions – including mild itch or rash
- Gastrointestinal disturbances
- Feeling strangely happy
- Joint or muscle pain
Other side effects of tranexamic acid include fatigue, headache, faintness, hypotension, and a runny or stuffy nose.
When we think about the clinical pharmacology of tranexamic acid, we must consider the following factors:
- Tranexamic acid is typically administered to hemophilia patients who must undertake a dental procedure, such as tooth extraction. It is taken before surgery, as well as for at least 8-days post-surgery.
- Tranexamic acid is administered IV before the dental procedure – dosed at 10mg per kg of patient. After surgery, the standard dose is 10mg per kg of patient for up to 8-days.
- Tranexamic acid is contraindicated in patients with a history of allergies to the drug. It should also be avoided in patients with a history of seizures because seizures have been reported in use with older patients or those undergoing cardiac surgery. TXA should also be avoided in cases of active thromboembolic disease due to the increased risk of blood clot formation. TXA should also be avoided in patients with severe renal damage due to the risk of drug accumulation.
- Intravenous TXA should be avoided in patients who are color blind or who have a disease that affects ocular vasculature.
- TXA should be stopped if patients are experiencing symptoms of a stroke or blood clot in the lung or leg.
- IV TXA has an approximate half-life of 2-hours, whereas the oral formulation has a half-life of 11-hours.
- Estrogen and progestin-containing contraceptives can enhance the pro-fibrinous activity of TXA. The combination should be avoided for this reason.
- Risk of thrombosis increases in patients who take Factor IX complex.
- Tretinoin can enhance the thrombogenic effect of tranexamic acid.
That concludes our study of tranexamic acid pharmacology. Check back to our pharmacy blog soon for more exclusive content to help you master the science of drugs and medicines!