What is the standard aspirin dose for suspected ACS in the EMS setting?

• A. 81 mg chewable
• B. 162-325 mg chewable
• C. 300 mg non-chewable
• D. 500 mg chewable

Answer: (B)

Aspirin works in ACS by rapidly inhibiting platelet aggregation through irreversible COX-1 inhibition, helping prevent further thrombus growth. The standard EMS approach is a single loading dose in the range of 162 to 325 mg, given as chewable tablets and chewed to speed absorption. Chewing accelerates onset, which is crucial when time matters in suspected ACS. Doses within this range provide fast, effective antiplatelet effect without the added risks of unnecessary higher amounts. A smaller dose like 81 mg would be too slow for this purpose, a 300 mg non-chewable form is swallowed and slower to act, and a 500 mg chewable exceeds the recommended amount. In practice, 325 mg chewable (or four 81 mg chewed) is commonly used as the initial dose, assuming no contraindications.