Tranexamic Acid (TXA)

Mechanism of Action

• Competitively inhibiting plasminogen activation - blocks the lysine binding sites on plasminogen, preventing its conversion to plasmin
• The resulting decrease in plasmin limits degradation of fibrin clots, preserving hemostasis
• It is 10 times more potent than the related drug aminocaproic acid
• Lippincott Illustrated Reviews: Pharmacology, p. 467
• Barash Clinical Anesthesia, 9e, p. 4514

Clinical Uses

1. Trauma and Major Hemorrhage

• The landmark CRASH-2 trial (>20,000 patients) showed TXA reduced all-cause mortality and death due to bleeding in trauma patients, with no increase in vascular occlusive events
• Benefit is only seen when given within 3 hours of injury - administration after 3 hours provides no benefit and may increase mortality
• The MATTERs study confirmed lower mortality in trauma patients receiving TXA, especially those requiring >10 units of packed red blood cells
• TXA should be used selectively - patients with "fibrinolytic shutdown" (the majority of trauma patients) may not benefit and could be harmed; it is most useful in true hyperfibrinolysis
• Barash Clinical Anesthesia, 9e

2. Traumatic Brain Injury (TBI)

• CRASH-3 trial (>12,000 patients): TXA reduced TBI-related death in mild-to-moderate TBI (RR 0.78, CI 0.64-0.95)
• Patients with reactive pupils had the greatest benefit
• No benefit in severe TBI
• No increase in vascular occlusive events or seizures
• Barash Clinical Anesthesia, 9e

3. Obstetric Hemorrhage / Postpartum Hemorrhage (PPH)

• ACOG recommends TXA when initial medical therapy for PPH fails
• TXA crosses the placenta and enters breast milk
• Widely used in intraoperative gynecologic and obstetric settings
• Miller's Anesthesia, 10e; Tintinalli's Emergency Medicine

4. Heavy Menstrual Bleeding (Menorrhagia)

• TXA is FDA-approved for the treatment of heavy menstrual bleeding
• Available as oral tablets (synthetic, orally active)
• Goodman & Gilman's Pharmacological Basis of Therapeutics

5. Dental Extraction in Patients with Hemostatic Defects

• Approved to prevent hemorrhage in patients with hemostatic disorders (e.g., hemophilia) undergoing tooth extraction
• Goodman & Gilman's

6. Epistaxis (Nosebleeds)

• Topical TXA has shown moderate-quality evidence for effectiveness in epistaxis management (systematic review and meta-analysis data)
• Rosen's Emergency Medicine

7. Orthopedic Surgery

• Long-established use in orthopedic procedures to reduce perioperative blood loss
• Barash Clinical Anesthesia, 9e

8. Melasma / Hyperpigmentation (Off-Label)

• UV radiation induces plasminogen activator in keratinocytes, stimulating melanogenesis; TXA inhibits this pathway
• Used topically (2-5% formulation, twice daily), intradermally (4 mg/mL), or orally (250-325 mg twice daily)
• Reduces UV-induced melanogenesis and neovascularization
• Goodman & Gilman's, p. 2667-2669

Pharmacokinetics

Adverse Effects

Key Contraindications / Cautions

• Active thromboembolic disease - TXA promotes clot stability, so existing thrombi are a contraindication
• Fibrinolytic shutdown in trauma - giving TXA to patients with already-suppressed fibrinolysis can worsen outcomes; patient selection is important
• Renal impairment - dose reduction needed as TXA is renally excreted; risk of seizures increases

Key Trials Summary

Tranexamic Acid in Dermatology

Why it Works on Skin - The Mechanism

• Arachidonic acid release
• Fibroblast growth factor (FGF) stimulation
• Vascular endothelial growth factor (VEGF) - causing increased neovascularization

• Goodman & Gilman's Pharmacological Basis of Therapeutics

Primary Indication: Melasma

• Monotherapy in resistant cases
• Adjunct to standard regimens (hydroquinone, tretinoin, topical steroids)
• Fitzpatrick's Dermatology, p. 1410
• Andrews' Diseases of the Skin

Routes of Administration and Dosing

• Goodman & Gilman's; Fitzpatrick's Dermatology

Intradermal injection = Microneedling > Oral > Topical

Other Skin Uses

Post-Inflammatory Hyperpigmentation (PIH)

• TXA is listed as one of the topical therapeutic options for PIH alongside hydroquinone, azelaic acid, kojic acid, niacinamide, and vitamin C
• Useful after acne, eczema, burns, or any inflammatory skin event
• Dermatology 2-Volume Set, 5e

General Hyperpigmentation

• TXA is included in the arsenal of skin-lightening agents used alongside kojic acid, arbutin, licorice extracts, niacinamide, and cysteamine
• Dermatology 2-Volume Set, 5e

Place in Melasma Treatment Algorithm

1. First line: Sunscreen (broad-spectrum, including visible light for dark skin types) - mandatory and enhances all other treatments
2. Gold standard topical: 4% hydroquinone +/- tretinoin + topical steroid (Kligman's formula)
3. Add TXA when: Treatment is resistant or relapsing, or as an adjunct in any form
4. Procedural options: Chemical peels, Q-switched Nd:YAG laser, fractional lasers (with caution - risk of PIH)
5. TXA advantage: Works on both epidermal AND dermal melanin - most topicals only address epidermal pigment

Adverse Effects (Skin-Specific Use)

Important: Before prescribing systemic (oral) TXA for skin, screen patients for thromboembolic risk (DVT history, thrombophilia, prolonged immobility, OCP use). The antifibrinolytic action is systemic even at low doses.

Recent Evidence (2025)

• Intradermal TXA injection is an effective alternative for melasma with advantages over other delivery routes as measured by MASI (Melasma Area and Severity Index)
• TXA injections outperformed the majority of non-TXA standard treatments