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Metformin and contrast with CKD — GPhC CRA MCQ

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HardEndocrine TherapeuticsMetformin and contrast with CKDGPhC CRA

A 63-year-old takes metformin 1 g twice daily and is booked for intravascular iodinated contrast. eGFR is 32 mL/min/1.73 m² and stable heart failure is treated with furosemide. What is the correct metformin plan?

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Correct answer: E — Stop at contrast; restart after 48 hours once renal function is stable

Intravascular iodinated contrast can precipitate renal deterioration and metformin accumulation. The SmPC directs that metformin be stopped before or at the imaging procedure and not restarted for at least 48 hours, after renal function has been re-evaluated and shown stable. Heart failure and diuretic use increase the importance of individual hydration and renal assessment; they do not justify an improvised sulfonylurea substitution.

Reference: Metformin SmPC: https://www.medicines.org.uk/emc/product/13160/smpc