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Opioid Tolerance Perioperative — RACP Adult Medicine MCQ

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ModerateClinical PharmacologyOpioid Tolerance PerioperativeRACP Adult Medicine

A 55-year-old man with chronic back pain on regular oxycodone 40 mg BD and paracetamol 1 g QID is admitted for elective spinal surgery. Postoperatively, despite his usual oxycodone dose, he reports severe pain rated 9/10. What is the most likely explanation?

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Correct answer: C — Opioid tolerance requiring higher doses

Patients on long-term opioid therapy develop pharmacological tolerance, requiring higher doses to achieve the same analgesic effect. The baseline oxycodone dose maintains their resting state but does not provide adequate analgesia for acute surgical pain. Management involves continuing their baseline opioid (to prevent withdrawal), adding multimodal analgesia (regional anaesthesia, ketamine infusion, NSAIDs if safe), and titrating additional opioid for acute pain. An acute pain service referral is appropriate.

Reference: AMH – 2025 – Opioid Analgesics; ANZCA – 2024 – Acute Pain Management Guidelines