Tranexamic acid
Tranexamic acid (TXA) is a medication used to treat or prevent excessive blood loss from major trauma, postpartum bleeding, surgery, tooth removal, nosebleeds, and heavy menstruation. It is also used for hereditary angioedema. It is taken either orally or by injection into a vein. Side effects are rare. Some include changes in color vision, blood clots, and allergic reactions. Greater caution is recommended in people with kidney disease. Tranexamic acid appears to be safe for use during pregnancy and breastfeeding. Tranexamic acid is an antifibrinolytic medication. Tranexamic acid was first made in 1962 by Japanese researchers Shosuke and  Utako Okamoto. It is on the World Health Organization's List of Essential Medicines. Tranexamic acid is available as a generic drug. Medical uses. Tranexamic acid is frequently used following major trauma. Tranexamic acid is used to prevent and treat blood loss in a variety of situations, such as dental procedures, heavy menstrual bleeding, and surgeries with high risk of blood loss. Trauma. Tranexamic acid has been found to decrease the risk of death in people who have significant bleeding due to trauma. It is most effective if taken within the first three hours following major trauma. It has been  shown to reduce death due to any cause and death due to bleeding. Further studies are assessing the effect of tranexamic acid in isolated brain injury. Given within three hours of a head injury it also decreases the risk of death. Menstrual bleeding. Tranexamic acid is sometimes used to treat heavy menstrual bleeding. When taken by mouth it both safely and effectively treats regularly occurring heavy menstrual bleeding and improves quality of life. Another study demonstrated that the dose does not need to be adjusted in females who are between ages 12 and 16. Childbirth. Tranexamic acid is sometimes used  (often in conjunction with oxytocin) to reduce bleeding after childbirth. Death due to postpartum bleeding is reduced in women receiving tranexamic acid. Dentistry. In the United States, tranexamic acid is FDA approved for short-term use in people with severe bleeding disorders who are about to have dental surgery. Tranexamic acid is used for a short period of time before and after the surgery to prevent major blood loss and decrease the need for blood transfusions. Tranexamic acid is used in dentistry in the form of a 5% mouth rinse after extractions or surgery in patients with prolonged bleeding time ; e.g., from acquired or inherited disorders. Hematology. There is not enough evidence to support the routine use of tranexamic acid to prevent bleeding in people with blood cancers. However, there are several trials that are currently assessing this use of tranexamic acid. For people with inherited bleeding disorders (e.g. von Willebrand's disease), tranexamic acid is often given. It has also been recommended for people with acquired bleeding disorders (e.g., directly acting oral anticoagulants (DOACs)) to treat serious bleeding. Nosebleeds. The use of tranexamic acid, applied directly to the area that is bleeding or taken by mouth, appears useful to  treat nose bleeding compared to packing the nose with cotton pledgets alone. It decreases the risk of rebleeding within 10 days. Experimental uses. Tranexamic acid might alleviate neuroinflammation in some experimental settings. Tranexamic acid can be used in case of postpartum hemorrhage; it can decrease the risk of death due to bleeding by one third according to the WHO. Adverse effects. Side effects are rare. Some reported adverse events include changes in color vision, blood clots, and allergic reactions such as anaphylaxis. Whether the risk of venous thromboembolism (blood clots) is actually increased is a matter of debate. The risk  is mentioned in the product literature, and they were reported in post marketing experience. Despite this, and the inhibitory effect of tranexamic acid on blood clot breakdown, large studies of the use of tranexamic acid have not shown an increase in the risk of venous or arterial thrombosis, even in people who had previously experienced thrombosis under other circumstances. Mechanism of action. Tranexamic acid is a synthetic analog of the amino acid lysine. It serves as an antifibrinolytic by reversibly binding four to five lysine receptor sites on plasminogen. This decreases the conversion of plasminogen to plasmin, preventing fibrin degradation  and preserving the framework of fibrin's matrix structure. Tranexamic acid has roughly eight times the antifibrinolytic activity of an older analogue, ε-aminocaproic acid. Tranexamic acid also directly inhibits the activity of plasmin with weak potency (IC = 87 mM), and it can block the active-site of urokinase plasminogen activator (uPA) with high specificity (Ki = 2 mM), one of the highest among all the serine proteases. Society and culture. Tranexamic acid was first synthesized in 1962 by Japanese researchers Shosuke and Utako Okamoto. It has been included in the WHO list of essential medicines. Brand names. Tranexamic  acid is marketed in the U.S. and Australia in tablet form as Lysteda and in Australia, Sweden and Jordan it is marketed in an IV form and tablet form as Cyklokapron, in the UK and Sweden as Cyclo-F. In the UK it is also marketed as Femstrual, in Asia as Transcam, in Bangladesh as Tracid, in India as Pause, in Pakistan as Transamin, in South America as Espercil, in Japan as Nicolda, in France, Poland, Belgium and Romania as Exacyl and in Egypt as Kapron. In the Philippines, its capsule form is marketed as Hemostan and in Israel as  Hexakapron. Approval. The U.S. Food and Drug Administration (FDA) approved tranexamic acid oral tablets (brand name Lysteda) for treatment of heavy menstrual bleeding on 13 November 2009. In March 2011 the status of tranexamic acid for treatment of heavy menstrual bleeding was changed in the UK, from PoM (Prescription only Medicines) to P (Pharmacy Medicines) and became available over the counter in UK pharmacies under the brand names of Cyklo-F and Femstrual, initially exclusively for Boots pharmacy, which has sparked some discussion about availability. (In parts of Europe it had then been available OTC for over a decade.) Regular  liver function tests are recommended when using tranexamic acid over a long period of time.