Opioid selection in renal impairment — GPhC CRA MCQ

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HardRenal and Hepatic ImpairmentOpioid selection in renal impairmentGPhC CRA

A palliative-care patient with eGFR 18 mL/min/1.73 m² develops drowsiness and myoclonus while taking modified-release morphine. Pain remains severe. Which pharmacy recommendation is safest?

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Correct answer: C — Pause morphine and arrange toxicity review before another opioid is selected

Pause morphine and arrange toxicity review before another opioid is selected: Morphine metabolites accumulate in severe renal impairment and the neurological features suggest toxicity; further doses should be withheld while urgent assessment and specialist opioid conversion, often to fentanyl or alfentanil, is arranged. Continue morphine, add haloperidol and review myoclonus within 24 hours: Treating the symptom while continuing the accumulating opioid risks worsening sedation and respiratory depression. Extend the morphine interval and review at the next palliative visit: Established toxicity requires prompt assessment rather than a routine interval change without supervision. Convert to codeine using the recorded oral-morphine dose and monitor pain: Codeine also produces renally cleared active metabolites and is unsuitable in severe renal impairment. Convert to renal-adjusted tramadol after calculating the equivalent daily dose: Tramadol requires renal adjustment and an unsupervised conversion is unsafe in a toxic, opioid-tolerant patient.

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