What is tranexamic acid?

What is Tranexamic Acid?

Tranexamic acid is an antifibrinolytic medication that works by blocking the breakdown of blood clots, thereby reducing bleeding in various clinical situations. 1

Mechanism of Action

Tranexamic acid is a synthetic derivative of the amino acid lysine that exerts its antifibrinolytic effect through reversible blockade of lysine binding sites on plasminogen molecules. 2 By binding to plasminogen, it blocks the interaction of plasmin(ogen) with fibrin, thereby preventing dissolution of the fibrin clot and stabilizing existing clots. 3

Chemical Structure and Formulation

• Tranexamic acid is chemically known as trans-4-(aminomethyl)cyclohexanecarboxylic acid, appearing as a white crystalline powder. 1
• The intravenous formulation contains 100 mg tranexamic acid per mL in sterile water for injection, with a pH of 6.5 to 8.0. 1

Primary Clinical Indications

Postpartum Hemorrhage (Most Robust Evidence)

• The WHO strongly recommends early intravenous tranexamic acid (within 3 hours of birth) for women with clinically diagnosed postpartum hemorrhage following vaginal birth or caesarean section. 4, 5
• The standard dosing regimen is 1 g (100 mg/mL) intravenously at 1 mL/min (over 10 minutes), with a second dose of 1 g if bleeding continues after 30 minutes or restarts within 24 hours. 4, 5
• Efficacy decreases by approximately 10% for every 15-minute delay in administration, with no benefit seen after 3 hours post-birth. 4, 6
• Administration beyond 3 hours after birth is potentially harmful and should be avoided. 4, 5

Trauma-Associated Hemorrhage

• Tranexamic acid significantly reduces all-cause mortality and death due to bleeding in trauma patients with significant bleeding, particularly when administered early after injury. 3
• Large-scale trials (CRASH-2) involving over 20,000 patients demonstrated mortality reduction when given within 3 hours of injury. 4

Surgical Bleeding

• Tranexamic acid reduces postoperative blood loss by 29-54% in cardiac surgery with cardiopulmonary bypass compared to placebo. 2
• It significantly reduces blood loss and transfusion requirements in total hip and knee replacement, prostatectomy, liver transplantation, and transurethral prostatic surgery. 2, 3

Hemophilia-Related Bleeding

• FDA-approved for patients with hemophilia for short-term use (2 to 8 days) to reduce or prevent hemorrhage and reduce the need for replacement therapy during and following tooth extraction. 1

Gynecological Bleeding

• Reduces menstrual blood loss by 34-57.9% versus placebo in women with menorrhagia. 2
• Effective in managing placental bleeding, postpartum hemorrhage, and bleeding after cervical conization. 2

Other Indications

• Upper gastrointestinal bleeding: Associated with mortality reductions of 40% based on meta-analysis. 2
• Traumatic hyphaema: Reduces rebleeding rates. 2, 3
• Hereditary angioneurotic oedema: Clinical benefit demonstrated. 2, 3

Route of Administration

• Tranexamic acid is administered intravenously, not intramuscularly. 6
• The WHO guidelines specifically state that recommendations apply to intravenous administration only, as benefits and potential harms of other routes remain a research priority. 6

Safety Profile and Contraindications

• Tranexamic acid is generally well tolerated, with nausea and diarrhea being the most common adverse events. 2
• Most adverse events are mild or moderate in severity; severe or serious events are rare. 3
• Absolute contraindication: Active intravascular clotting or history of thromboembolic events during pregnancy. 6
• Increased risk of thrombosis has not been demonstrated in clinical trials despite theoretical concerns. 2, 7

Clinical Context and Integration

• Tranexamic acid should be considered part of standard treatment packages for postpartum hemorrhage, alongside fluid replacement, uterotonics, monitoring of vital signs, and non-surgical/surgical interventions as needed. 4, 5
• Health facilities providing emergency obstetric care need appropriate supplies and trained staff to administer tranexamic acid safely by intravenous infusion. 5
• The drug has been in clinical use since it was first patented in 1957, with an expanding evidence base supporting its efficacy across diverse bleeding conditions. 8