Lithium Drug Interactions — MFDS Part 1 MCQ

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HardPharmacologyLithium Drug InteractionsMFDS Part 1

A patient taking modified-release lithium carbonate for bipolar disorder has stable serum lithium concentrations and normal renal function. Following surgical removal of a mandibular third molar, which commonly used dental drug is most likely to increase the serum lithium concentration and should generally be avoided unless use is unavoidable and closer lithium monitoring is arranged?

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Correct answer: E — Ibuprofen

Ibuprofen is an NSAID and can reduce renal lithium clearance, increasing the serum lithium concentration and risk of toxicity. Lithium has a narrow therapeutic window; its SmPC therefore recommends more frequent serum monitoring when an NSAID is started or stopped. An NSAID should generally be avoided when an effective alternative is available, with liaison with the lithium prescriber if its use is unavoidable. Paracetamol does not have this clinically important renal interaction and is usually the more appropriate analgesic. Amoxicillin is not among the antibiotics specifically identified in the lithium SmPC as increasing lithium concentrations. Lidocaine with adrenaline and topical chlorhexidine do not materially affect renal lithium clearance.

Reference: Electronic Medicines Compendium, Lithium Carbonate Essential Pharma 250 mg film-coated tablets, Summary of Product Characteristics, sections 4.2 and 4.5, text revised 26 November 2024. https://www.medicines.org.uk/emc/product/10828/smpc