tranexamic acid
Summary
Tranexamic acid is an antifibrinolytic agent that inhibits plasminogen activation, preventing clot breakdown. It's used to reduce bleeding in trauma, surgery, and heavy menstrual bleeding by stabilizing existing clots.
Detail
Tranexamic acid is a synthetic lysine analog that competitively inhibits plasminogen activation to plasmin, thereby preventing fibrin clot dissolution. It binds to lysine-binding sites on plasminogen, blocking its conversion to plasmin by tissue plasminogen activator (tPA). This mechanism preserves hemostatic clots and reduces bleeding. Clinically, it's used in trauma patients with significant hemorrhage (reduces mortality when given within 3 hours), cardiac surgery, orthopedic procedures, and heavy menstrual bleeding (menorrhagia). The drug has good oral bioavailability and is primarily renally excreted. Key contraindications include active thromboembolic disease due to increased thrombosis risk. Common side effects include nausea, diarrhea, and rarely seizures with high doses. The CRASH-2 trial demonstrated mortality benefit in trauma patients, making it a standard treatment in hemorrhage protocols.
Sources
- Goodman & Gilman's Pharmacological Basis of Therapeutics
- Hematology: Basic Principles and Practice (Hoffman)
- CRASH-2 trial (Lancet 2010)
- First Aid for the USMLE Step 1
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