Carbamazepine interaction — DFSRH MCQ

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HardPharmacologyCarbamazepine interactionDFSRH

A 31-year-old woman taking carbamazepine for epilepsy asks for contraception and declines an IUD. She wants a method unaffected by enzyme induction. What is the most appropriate contraceptive method?

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Correct answer: D — Depot medroxyprogesterone acetate injection

The best answer is “Depot medroxyprogesterone acetate injection”. Carbamazepine induces enzymes and reduces effectiveness of implant, POP and CHC. DMPA effectiveness is not significantly affected. Extended cycling does not overcome strong enzyme induction. Intrauterine-method decisions require separation of expected bleeding from pregnancy, partial expulsion, perforation and pelvic infection. Device position, pregnancy risk, recent intercourse and clinical stability determine whether treatment, removal, imaging or emergency contraception is needed. Pelvic infection is treated promptly, but an IUD is not removed routinely when the patient is improving on appropriate antibiotics.

Reference: CoSRH/FSRH, Intrauterine Contraception (March 2023, amended January 2025): https://www.cosrh.org/Common/Uploaded%20files/documents/fsrh-clinical-guideline-intrauterine-contraception-mar-23-amended.pdf