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Pharmacology · single question

Ibuprofen's mechanism of action is BEST described as:

  1. Mu-opioid receptor agonist
  2. Non-selective, irreversible COX-1 and COX-2 inhibitor
  3. Non-selective, reversible COX-1 and COX-2 inhibitor
  4. Selective, irreversible COX-2 inhibitor
Show answer and explanation

Correct answer: C. Non-selective, reversible COX-1 and COX-2 inhibitor

  • A. Mu-opioid agonists (morphine, oxycodone, fentanyl) work through opioid receptors — not the mechanism of ibuprofen.
  • B. Aspirin is a non-selective, IRREVERSIBLE COX inhibitor (permanently acetylates COX active site). Ibuprofen's inhibition is reversible.
  • C. Correct. Ibuprofen is a non-selective, reversible inhibitor of both COX-1 and COX-2 enzymes, preventing prostaglandin synthesis. It provides analgesia, antipyresis, and anti-inflammatory effects. Unlike aspirin (irreversible), ibuprofen's effect wears off when the drug is cleared.
  • D. Selective COX-2 inhibitors (e.g., celecoxib) spare COX-1 (gastroprotective), reducing GI side effects — ibuprofen is non-selective.

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