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Morphine in renal impairment — GPhC CRA MCQ

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HardCNS TherapeuticsMorphine in renal impairmentGPhC CRA

A patient using a stable fentanyl patch develops marked drowsiness after placing a heat pad over the application site. What is the likely mechanism?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — External heat increased transdermal absorption and opioid exposure

Heat increases cutaneous blood flow and fentanyl release/absorption, which can produce fatal respiratory depression. The heat source should be removed, the patch managed according to urgent clinical advice, and emergency assessment arranged for significant drowsiness or slow breathing.

Reference: BNF: fentanyl: https://bnf.nice.org.uk/drugs/fentanyl/