Tranexamic Acid Mechanism — ORE Part 1 MCQ
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Correct answer: B — Competitively inhibits conversion of plasminogen to plasmin
**A is correct.** Tranexamic acid is an antifibrinolytic: it competitively inhibits activation of plasminogen to plasmin. As plasmin mediates fibrin degradation, this reduces fibrinolysis and helps preserve the extraction-site clot. This is the relevant mechanism whether tranexamic acid is used systemically or topically as a mouthwash. **B** concerns primary haemostasis; tranexamic acid does not increase platelet adhesion or aggregation. **C** would enhance coagulation-factor activation, whereas tranexamic acid does not activate the intrinsic or common coagulation pathways. **D** describes the action of a vasoconstrictor, not an antifibrinolytic. **E** describes a local haemostatic dressing; tranexamic acid acts biochemically rather than by forming a physical barrier.
Reference: Sovereign Medical. Tranexamic Acid 500 mg Tablets: Summary of Product Characteristics, section 5.1 Pharmacodynamic properties. Revised 08 April 2026. https://www.medicines.org.uk/emc/product/14622/smpc