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Oral to SC Morphine — SCE Medical Oncology MCQ

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EasySupportive & Palliative OncologyOral to SC MorphineSCE Medical Oncology

A 58-year-old man with cancer on strong opioids is being switched from oral morphine to a subcutaneous morphine syringe driver. What is the oral-to-subcutaneous morphine conversion ratio?

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

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Correct answer: E — Oral morphine to SC morphine = 2:1 (halve the oral dose) — SC morphine is approximately twice as potent as oral morphine due to avoiding first-pass hepatic metabolism

Opioid conversion: oral morphine → SC morphine = divide by 2 (e.g. oral 60mg/24h = SC 30mg/24h). Oral morphine → oral oxycodone = divide by 1.5-2. Oral morphine → SC diamorphine = divide by 3. Oral morphine → transdermal fentanyl: specialist calculation. Always use conservative initial conversion with breakthrough doses available.

Reference: BNF; NICE CG140; Palliative Care Formulary