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Lithium and NSAIDs — GPhC CRA MCQ

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HardDrug InteractionsLithium and NSAIDsGPhC CRA

A 72-year-old woman stable on lithium carbonate 400 mg at night presents a prescription for naproxen 500 mg twice daily for back pain. Her last lithium level was 0.7 mmol/L and eGFR is 48 mL/min/1.73 m². What is the most important interaction to flag?

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Correct answer: B — Naproxen can increase lithium concentrations and toxicity risk

NSAIDs can reduce renal lithium clearance and raise lithium levels, particularly in older people and those with impaired renal function. The risk is toxicity with tremor, confusion, ataxia, diarrhoea or worsening renal function. The prescriber should be contacted to consider an alternative analgesic and lithium monitoring. This is more clinically important than a routine counselling point.

Reference: https://www.pharmacyregulation.org/students-and-trainees/pharmacist-education-and-training/registration-assessment