NPLEX II Pharmacology Practice Test

Aspirin works as an antiplatelet by irreversibly inhibiting cyclooxygenase-1 in platelets, which stops the production of thromboxane A2 and prevents platelet aggregation. Because platelets cannot synthesize new COX, this effect lasts for the life of the platelet, making low-dose aspirin a classic choice for preventing myocardial infarction in at‑risk individuals. A critical safety point is its association with Reye's syndrome in children, particularly if given during a viral illness, which is why aspirin is avoided in pediatric patients. The other options don’t fit as well: clopidogrel is an antiplatelet but not the standard MI prophylaxis described here and isn’t notably linked to Reye’s syndrome; warfarin is an anticoagulant, not an antiplatelet, and amoxicillin is an antibiotic.