A 55-year-old man on low-dose aspirin for coronary artery disease is scheduled for elective cholecystectomy. Aspirin irreversibly inhibits cyclooxygenase-1 in platelets. How long after the last aspirin dose should surgery be delayed to allow restoration of normal platelet function?
- A 7-10 days ✓
- B 3-4 days
- C 12-24 hours
- D 21 days
Correct answer: A. 7-10 days
Explanation
Aspirin irreversibly acetylates COX-1, blocking thromboxane C2 synthesis for the platelet's entire lifespan. New platelets must enter the circulation to restore function. Platelet lifespan is 7-10 days, and adequate hemostasis returns when about 10-20% of platelets are functional, typically 7-10 days after the last dose. Waiting only 12-24 hours is insufficient.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
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