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Valproate and lamotrigine — GPhC CRA MCQ

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HardDrug InteractionsValproate and lamotrigineGPhC CRA

A patient taking sodium valproate is started on lamotrigine by a specialist. The prescription appears to use a standard rapid lamotrigine titration schedule. What is the most important interaction to flag?

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Correct answer: D — Valproate increases lamotrigine exposure and rash risk

Valproate inhibits lamotrigine metabolism, increasing lamotrigine exposure and risk of serious skin reactions. Lamotrigine titration must be adjusted when used with valproate. The prescription should be checked against specialist instructions before supply. Patients should be counselled to seek urgent advice for rash, fever or mucosal symptoms.

Reference: BNF