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Lamotrigine and combined oral contraception — GPhC CRA MCQ

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HardCNS TherapeuticsLamotrigine and combined oral contraceptionGPhC CRA

A patient stabilised on lamotrigine for bipolar disorder starts a combined oral contraceptive pill from an online provider. She asks whether the new pill matters as her mood has been stable. What is the most important interaction to flag?

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Correct answer: B — Oestrogen may reduce lamotrigine concentrations and destabilise symptom control

Oestrogen-containing contraceptives can increase lamotrigine clearance and lower lamotrigine exposure. This may reduce symptom or seizure control, depending on the indication. Concentrations may rise during pill-free intervals, so changes should be managed with the prescriber. Lamotrigine is not a strong enzyme inducer in the way carbamazepine is.

Reference: BNF; FSRH