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Valproate and lamotrigine — GPhC CRA MCQ

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ModerateDrug InteractionsValproate and lamotrigineGPhC CRA

A patient taking sodium valproate is prescribed lamotrigine by a specialist. The patient asks why the dose schedule starts very low and increases slowly. What is the most important interaction to flag?

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

Sodium valproate inhibits lamotrigine metabolism and increases lamotrigine exposure. This increases the risk of serious skin reactions, so slow titration is essential. The patient should be counselled to seek urgent advice if a rash develops. Lamotrigine does not remove valproate pregnancy-related risks.

Reference: BNF