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Carbamazepine and contraception — GPhC CRA MCQ

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ModerateCNS TherapeuticsCarbamazepine and contraceptionGPhC CRA

A 31-year-old woman taking carbamazepine for epilepsy requests a combined oral contraceptive pill. She has no contraindications to oestrogen. She asks for the most reliable option while continuing carbamazepine. What is the most important interaction to flag?

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Correct answer: E — Carbamazepine can reduce hormonal contraceptive efficacy through enzyme induction

Carbamazepine is an enzyme inducer and can reduce the effectiveness of many hormonal contraceptives. Long-acting methods unaffected by enzyme induction, such as copper intrauterine contraception, should be discussed or arranged. Emergency contraception choices are also affected by enzyme induction.

Reference: BNF; FSRH guidance