Physiology & Biochemistry · patient case question
What is the mechanism of action of the ibuprofen planned for her postoperative analgesia?
Patient case: Family History and a Preoperative Workup
Patient: 26-year-old female
Chief Complaint: “My wisdom teeth need to come out and I want to make sure everything is safe first.”
Background: Multiple sclerosis diagnosed 2 years ago, currently in remission. Total thyroidectomy 6 months ago for papillary thyroid carcinoma, with persistent hoarseness since surgery. Her mother is a known carrier of Duchenne muscular dystrophy. Her brother has hemophilia A. She is planning a pregnancy within the next year.
Medications: Levothyroxine · Glatiramer acetate
Vital Signs: BP 114/70 mmHg · HR 76 bpm · RR 16 · T 98.4°F
Findings: Persistently breathy, hoarse voice. Well-healed anterior neck incision. Four impacted third molars planned for removal. Ibuprofen is planned for postoperative analgesia.
Show answer and explanation
Correct answer: C. Reversible, non-selective inhibition of cyclooxygenase
- A. Incorrect. 5-lipoxygenase inhibition describes zileuton, used in asthma to block leukotriene synthesis. It is not an analgesic.
- B. Incorrect. Selective COX-2 inhibition describes celecoxib, which spares gastric mucosal prostaglandin synthesis but carries increased cardiovascular risk.
- C. Correct. Ibuprofen competitively and reversibly inhibits both COX-1 and COX-2, reducing prostaglandin synthesis. This produces its analgesic, anti-inflammatory, and antipyretic effects, and the reversibility means platelet function recovers as the drug is cleared.
- D. Incorrect. Irreversible cyclooxygenase inhibition describes aspirin, which acetylates the enzyme permanently. Because platelets cannot synthesize new enzyme, the antiplatelet effect persists for the platelet lifespan of 7 to 10 days.
Note: Interaction worth noting: ibuprofen competes with aspirin for the platelet COX-1 binding site and can blunt aspirin’s cardioprotective effect if taken beforehand.
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