Clopidogrel Mechanism — MFDS Part 1 MCQ
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Correct answer: C — Irreversible inhibition of platelet P2Y12 ADP receptors
Clopidogrel is converted by CYP450 enzymes to an active thiol metabolite that irreversibly inhibits platelet P2Y12 ADP receptors. This prevents ADP-mediated activation of the glycoprotein IIb/IIIa complex and thereby reduces platelet aggregation. Affected platelets remain inhibited for the remainder of their approximately 7–10-day lifespan. Cyclooxygenase-1 inhibition is the principal antiplatelet mechanism of aspirin. Glycoprotein IIb/IIIa antagonists act directly at the final common receptor for platelet aggregation, whereas clopidogrel only inhibits its downstream activation. Clopidogrel does not act by directly inhibiting thromboxane synthase or by increasing endothelial prostacyclin production.
Reference: Electronic Medicines Compendium, Clopidogrel 75 mg film-coated tablets, Summary of Product Characteristics, section 5.1 Pharmacodynamic properties, revised 10 June 2026. https://www.medicines.org.uk/emc/product/5207/smpc