Pharmacology · single question
A patient on warfarin and aspirin (dual therapy) presents with bleeding gums. Which of these medications MOST directly affects platelet function?
Show answer and explanation
Correct answer: D. Aspirin
Aspirin (and clopidogrel) irreversibly inhibits COX-1, preventing thromboxane A2 synthesis, which permanently impairs platelet aggregation for the platelet's lifetime (~7–10 days). Warfarin affects clotting factor production (II, VII, IX, X) — it does not directly impair platelet function but prolongs clotting time via the coagulation cascade. The question specifically asks about platelet function — that's aspirin/clopidogrel.
- A. ❌ Warfarin and aspirin work through completely different mechanisms; aspirin specifically affects platelet function.
- B. ❌ While gingivitis contributes to bleeding, the medications are what directly impairs hemostasis mechanisms.
- C. ❌ Warfarin inhibits vitamin K-dependent clotting factors — it affects the coagulation cascade, NOT platelet function.
- D. ✅ CORRECT – Aspirin irreversibly inhibits platelet COX-1, permanently preventing thromboxane A2-mediated platelet aggregation.