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Pharmacology · single question

The mechanism of action of aspirin is:

  1. Irreversible inhibition of cyclooxygenase (COX-1 and COX-2)
  2. Reversible inhibition of COX
  3. Selective COX-2 inhibition
  4. Inhibition of lipoxygenase
Show answer and explanation

Correct answer: A. Irreversible inhibition of cyclooxygenase (COX-1 and COX-2)

  • A. Correct. Aspirin irreversibly acetylates COX-1 and COX-2, reducing prostaglandin/thromboxane synthesis. In platelets this lasts the platelet's lifespan (~7–10 days).
  • B. Other NSAIDs (e.g., ibuprofen) reversibly inhibit COX; aspirin is irreversible.
  • C. Celecoxib is the selective COX-2 inhibitor, not aspirin.
  • D. Aspirin inhibits COX, not lipoxygenase.

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