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Morphine in renal impairment — GPhC CRA MCQ

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HardRenal and Hepatic ImpairmentMorphine in renal impairmentGPhC CRA

A patient used 60 mg modified-release oral morphine plus two 10 mg oral rescue doses in the last 24 hours. Using an oral-to-subcutaneous morphine ratio of 2:1, what 24-hour subcutaneous dose is calculated?

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Correct answer: A — Forty milligrams over 24 hours before separate rescue-dose calculation

Total oral morphine use is 60 + 10 + 10 = 80 mg in 24 hours. At the stated 2:1 oral-to-subcutaneous ratio, 80 ÷ 2 = 40 mg subcutaneously over 24 hours. Clinical review must confirm indication, renal function, frailty and an appropriate rescue dose.

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