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Lithium and NSAIDs — GPhC CRA MCQ

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HardCNS TherapeuticsLithium and NSAIDsGPhC CRA

A 58-year-old woman taking lithium carbonate modified-release 400mg twice daily asks for ibuprofen gel and tablets for knee pain. She has had vomiting and poor fluid intake for two days. Her last lithium level was three months ago. What is the most important interaction to flag?

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Correct answer: C — NSAIDs and dehydration can increase lithium toxicity risk

Lithium has a narrow therapeutic index and toxicity risk rises with dehydration and medicines that reduce renal clearance, including NSAIDs. Vomiting and poor intake are additional red flags. The patient needs advice to avoid oral NSAIDs unless a prescriber has assessed risk, and she may need urgent lithium level and renal function assessment. Topical NSAID risk may be lower but still warrants caution in context.

Reference: BNF