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Lithium and ACE inhibitor — GPhC CRA MCQ

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HardDrug InteractionsLithium and ACE inhibitorGPhC CRA

A patient taking lithium for bipolar disorder is prescribed lisinopril for hypertension. Their lithium levels have been stable. What is the most important interaction to flag?

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Correct answer: C — Increased lithium concentration and toxicity risk

ACE inhibitors can reduce lithium clearance and increase toxicity risk. The prescriber should be contacted and levels monitored if treatment proceeds. In this scenario, the correct option is increased lithium concentration and toxicity risk. The other options are plausible but do not address the key clinical, legal or safety issue as directly. This aligns with UK pharmacy practice guidance cited in the reference field.

Reference: BNF; Stockley's Drug Interactions