Which aspirin regimen is recommended in suspected myocardial infarction?

• A. 81 mg PO daily
• B. 160 mg IV
• C. 324 mg PO
• D. 500 mg PO

Answer: (C)

In suspected myocardial infarction, the priority is rapid platelet inhibition to reduce mortality. Aspirin achieves this by irreversibly inhibiting COX-1 in platelets, lowering thromboxane A2 and preventing further platelet aggregation. The key is a prompt loading dose given orally and chewed to speed absorption.

The recommended loading dose is about 325 mg (often given as a non-enteric-coated tablet and chewed) to ensure rapid onset. After this, continue with a low maintenance dose, typically 81 mg daily, for ongoing protection if there are no contraindications.

Smaller daily doses alone don’t provide the quick, robust antiplatelet effect needed acutely. Intravenous aspirin isn’t standard in this setting, and a higher single dose like 500 mg isn’t the guidelineed approach. Thus, the best regimen is the oral loading dose of around 325 mg followed by maintenance therapy.