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Gabapentin renal dosing — GPhC CRA MCQ

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HardCNS TherapeuticsGabapentin renal dosingGPhC CRA

A 76-year-old with neuropathic pain has a documented Cockcroft–Gault creatinine clearance of 24 mL/min. Gabapentin 300 mg three times daily was started yesterday while morphine modified-release was continued. After two doses she is markedly drowsy but rousable, with a respiratory rate of 12/min. What is the safest action before the next gabapentin dose?

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Correct answer: B — Withhold gabapentin and obtain a same-day review of renal dosing and combined sedation

The stem supplies Cockcroft–Gault CrCl directly, so no eGFR-to-CrCl inference is needed. At CrCl 15–29 mL/min, the licensed total daily gabapentin range is 150–600 mg; 900 mg/day is outside it. New marked drowsiness after initiation while morphine is continued is a clinically important additive CNS-depression signal. Withhold further gabapentin and obtain same-day review of renal dosing and the complete sedative regimen rather than selecting a replacement dose before that assessment.

Reference: Gabapentin SmPC: https://www.medicines.org.uk/emc/product/14230/smpc