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Enzyme induction and emergency contraception — GPhC CRA MCQ

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ModerateDrug InteractionsEnzyme induction and emergency contraceptionGPhC CRA

A woman using carbamazepine had unprotected sex 36 hours ago and asks for emergency contraception. What is the most important interaction to flag?

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Correct answer: B — Carbamazepine can reduce levonorgestrel emergency contraception effectiveness

Carbamazepine is an enzyme inducer and can reduce effectiveness of levonorgestrel emergency contraception. A copper intrauterine device is the most effective option and specialist referral should be discussed. If oral methods are considered, guidance must be followed carefully.

Reference: BNF; FSRH guidance