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Metformin renal function — GPhC CRA MCQ

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HardEndocrine TherapeuticsMetformin renal functionGPhC CRA

A 71-year-old taking metformin has stable eGFR 28 mL/min/1.73 m². Which pharmacokinetic feature makes continued treatment unsafe?

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Correct answer: C — Predominantly renal elimination of unchanged metformin

Metformin is eliminated largely unchanged by the kidneys. Markedly reduced renal function increases systemic exposure and the risk of metformin-associated lactic acidosis, particularly during acute hypoxia, sepsis or kidney injury. An eGFR below 30 mL/min/1.73 m² normally requires stopping treatment and prescriber review.

Reference: https://bnf.nice.org.uk/drugs/metformin-hydrochloride/