Tranexamic acid is an antifibrinolytic agent and inhibits the dissolution of blood clots. The substance is used to stop and prophylaxis bleeding caused by hyperfibrinolysis.
What is tranexamic acid?
The substance tranexamic acid is an antifibrinolytic agent. It inhibits the fibrinolytic system and thus ultimately inhibits clot dissolution (fibrinolysis). Tranexamic acid is produced exclusively synthetically and is similar to lysine. The substance belongs to the group of para-aminocarboxylic acids. Tranexamic acid is readily soluble in water, but poorly soluble in ethanol and diethyl ether. The substance exists in a solid aggregate state as a beige-colored solid, the melting point is between 386 and 392 degrees Celsius. At these temperatures, decomposition of the substance takes place. The molar mass of tranexamic acid is 157.21g x mol ^-1. The chemical formula of the substance is C8H15NO2.
Pharmacological action
Tranexamic acid is administered perorally, intravenously, or locally. The bioavailability of the substance after peroral administration is 30-50% and is not affected by concomitant food intake. Plasma protein binding is 3%, with the substance bound almost exclusively to plasmin. Tranexamic acid is 100% placental but only one percent breastmilk compatible. Metabolization occurs slightly in the liver, and 95% of the substance is excreted unchanged in the urine. There is no excretion in the stool. The half-life of tranexamic acid is 2 hours. Pharmacodynamically, the drug causes blockage of the formation of plasmin. This blockage occurs through inhibition of the proteolytic activity of plasminogen activators. Overall, this results in plasmin being impeded in its ability or task to dissolve (lyse) fibrin. When tranexamic acid is dosed low, it acts as a competitive inhibitor of plasmin, but at higher doses it is a non-competitive inhibitor. Metabolism in the liver is very minor, as mentioned above, and 95% of elimination is renal. If tranexamic acid is administered together with factor IX, the risk of thrombosis increases. Due to the almost exclusively renal elimination, the dose must be adjusted in case of renal insufficiency. The active substance is administered orally in the form of tablets or effervescent tablets. In addition, intravenous administration is possible. Because the substance is also active in urine, it can also be used to treat bleeding in the urinary tract.
Medical application and use
Tranexamic acid is an antifibrinolytic agent. The substance is used medically for therapy in bleeding due to hyperfibrinolysis, increased blood clot dissolution, and for prophylaxis of bleeding due to possible hiberfibrinolysis. In addition, tranexamic acid is used as an antidote for bleeding during fibrinolytic therapy. Other indications include the promotion of coagulation in postnatal (postpartum) hemorrhage, prophylaxis of bleeding during dental procedures in high-risk patients, and bleeding prophylaxis in surgical procedures with a high risk of bleeding. Furthermore, tranexamic acid is used in hypermenorrhea, as an adjunctive medication in the administration of fibrinogen and in hereditary angioedema. In cases of nosebleeds, it can be applied by means of a nebulizer.
Risks and side effects
Side effects of tranexamic acid include allergies, skin rashes, increased risk of theombosis in patients with a predisposition to it (this can result in myocardial infarction, stroke, and pulmonary embolism), atrial fibrillation, and visual disturbances. The risk of thrombosis is further increased with concomitant administration of factor IX. Tranexamic acid must not be taken in cases of pre-existing thrombosis, nor during breastfeeding. In cases of severe bleeding in the urinary tract, coagulum (“blood clots”) may form, which can lead to urinary retention. Furthermore, there are relative contraindications, for example in case of consumption coagulopathy. Here, the individual risk must be weighed up by the physician. The same applies to bleeding in the urinary tract. Tranexamic acid is effective here, but there is a risk of coagulum formation, which can cause urinary retention. This is therefore also a relative contraindication in which the risk must be weighed up by the physician.Tranexamic acid is available by prescription and thus may only be administered or prescribed by a physician, as administration must always be preceded by a diagnostic evaluation and consideration of the individual risk.
