What is tranexamic acid and what is it used for?

Tranexamic Acid: An Antifibrinolytic Agent for Hemorrhage Control

Tranexamic acid is an antifibrinolytic medication that prevents blood clot breakdown by inhibiting plasminogen activation, making it highly effective in reducing mortality and blood loss in various hemorrhagic conditions including trauma, postpartum hemorrhage, and surgical bleeding.

Mechanism of Action

Tranexamic acid (TXA) is a synthetic lysine analogue that:

• Competitively inhibits plasminogen activation and plasmin activity
• Blocks the interaction between plasmin(ogen) and fibrin
• Prevents dissolution of fibrin clots
• Has a plasma half-life of approximately 120 minutes 1

Clinical Applications

Trauma Management

• Trauma with significant bleeding: TXA reduces all-cause mortality and death due to bleeding, especially when administered within 3 hours of injury 2
• Dosing: 1g loading dose over 10 minutes followed by 1g infused over 8 hours 1, 2
• Timing is critical: Administration within 3 hours of injury reduces hemorrhage death by approximately one-third 2

Obstetric Hemorrhage

• Postpartum hemorrhage: WHO strongly recommends early use (within 3 hours of birth) for clinically diagnosed postpartum hemorrhage 1
• Dosing: 1g IV over 10 minutes, with a second 1g dose if bleeding continues after 30 minutes or restarts within 24 hours 1
• Indication: For blood loss >500mL after vaginal birth, >1000mL after cesarean section, or any blood loss compromising hemodynamic stability 1

Surgical Applications

• Cardiac surgery: Reduces perioperative blood loss by 29-54% compared to placebo 3
• Orthopedic surgery: Effective in reducing blood loss in total hip and knee replacements 4
• Prostatectomy and liver transplantation: Significantly reduces blood loss 4, 3

Other Indications

• Hemophilia: FDA-approved for short-term use (2-8 days) to prevent hemorrhage during and following tooth extraction 5
• Heavy menstrual bleeding: Reduces menstrual blood loss by 34-58% 3
• Upper gastrointestinal bleeding: Associated with mortality reduction of 5-54% 3
• Traumatic hyphema: Reduces rates of rebleeding 3

Dosing Considerations

• Standard dosing: 10 mg/kg IV followed by infusion of 1 mg/kg/hour 3
• Renal impairment: Dose reduction required as TXA is primarily excreted by the kidneys 1, 5
• Route of administration: Primarily given intravenously; oral formulations are available for certain indications 1

Safety Profile and Contraindications

Contraindications

• Subarachnoid hemorrhage: Risk of cerebral edema and cerebral infarction 5
• Active intravascular clotting: May exacerbate thrombotic events 5
• Severe hypersensitivity to tranexamic acid or any ingredients 5

Adverse Effects

• Common: Nausea, vomiting, diarrhea, allergic dermatitis, giddiness, hypotension 5
• Thrombotic risk: Despite theoretical concerns, meta-analyses of clinical trials have not demonstrated increased risk of arterial or venous thrombotic events in surgical or trauma settings 1
• Special caution: Use carefully in patients with massive hematuria (risk of ureteric obstruction) and patients on oral contraceptives 1

Clinical Pearls

• TXA should be administered as early as possible in trauma and postpartum hemorrhage for maximum benefit
• The drug is remarkably cost-effective in trauma and surgical settings 4
• Unlike aprotinin (another antifibrinolytic), TXA does not require a test dose and has fewer safety concerns 1
• TXA is superior to many other hemostatic agents (etamsylate, flurbiprofen, mefenamic acid) for heavy menstrual bleeding 4

Comparison to Other Antifibrinolytics

• Epsilon-aminocaproic acid: TXA is at least as effective but has 10-fold greater potency 1, 4
• Aprotinin: Similar efficacy to TXA but aprotinin has more safety concerns and higher cost 1
• Desmopressin: TXA is more effective in surgical procedures and heavy menstrual bleeding 4

The wide application of tranexamic acid across multiple clinical scenarios demonstrates its versatility and effectiveness as a hemostatic agent, with a favorable safety profile when used appropriately.