Gabapentin renal dosing — GPhC CRA MCQ
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Correct answer: D — Withhold sedating doses and arrange urgent toxicity and renal-dose review
Withhold sedating doses and arrange urgent toxicity and renal-dose review: Gabapentin is renally eliminated and morphine has active renally cleared metabolites; marked drowsiness may precede respiratory depression and needs assessment before either regimen is merely adjusted. Reduce gabapentin to twice daily and continue morphine pending review: A partial empirical reduction is inadequate when clinically important combined toxicity is already suspected. Continue gabapentin and omit only the next modified-release morphine dose: Both treatments may be contributing in severe renal impairment, so selective self-management without assessment is unsafe. Replace morphine with the same milligram dose of codeine: Codeine also has problematic renally cleared active metabolites and opioid conversion is not milligram-for-milligram. Continue both regimens and recheck eGFR at routine review: The current marked drowsiness is an urgent toxicity signal, not a finding for deferred routine monitoring.
Reference: BNF: gabapentin: https://bnf.nice.org.uk/drugs/gabapentin/; BNF: morphine: https://bnf.nice.org.uk/drugs/morphine/