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Metformin and iodinated contrast — GPhC CRA MCQ

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ModerateDrug InteractionsMetformin and iodinated contrastGPhC CRA

A patient taking metformin is booked for contrast imaging and has reduced renal function. What is the most important interaction to flag?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: E — Increased risk of lactic acidosis if renal function worsens

Contrast-associated renal impairment can increase metformin-associated lactic acidosis risk. In this vignette, "Increased risk of lactic acidosis if renal function worsens" is the safest single best answer. The other options are less appropriate because they miss the key clinical risk, conflict with UK medicines guidance, or delay needed review.

Reference: BNF