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ART Drug Interaction — SCE Infectious Diseases MCQ

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ModerateHIV MedicineART Drug InteractionSCE Infectious Diseases

A 28-year-old woman with HIV on DTG/TAF/FTC develops symptoms of depression. Her GP prescribes Carbamazepine. What is the critical drug interaction?

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Correct answer: C — Carbamazepine is a potent CYP3A4/UGT1A1 inducer that significantly reduces Dolutegravir levels — it is contraindicated with DTG at standard dose

Carbamazepine is a potent enzyme inducer (CYP3A4, UGT1A1, P-gp) that reduces Dolutegravir plasma levels by approximately 50%. Co-administration at standard DTG dose (50 mg OD) is contraindicated. If Carbamazepine cannot be avoided, DTG must be increased to 50 mg BD. However, switching to an anticonvulsant without enzyme-inducing properties (Lamotrigine, Levetiracetam, Sodium Valproate — noting Valproate's teratogenicity in women of childbearing potential) is preferable. The Liverpool Drug Interactions database should always be checked.

Reference: BHIVA 2025 – ART guidelines; BNF 2024 – Carbamazepine interactions; Liverpool HIV Interactions