Methadone-Buprenorphine Switch Threshold — MRCPsych Paper B MCQ

Instant feedback + full explanation. One question, done properly.

ModerateSubstance MisuseMethadone-Buprenorphine Switch ThresholdMRCPsych Paper B

A 40-year-old man with opioid dependence is prescribed methadone 80 mg daily and wishes to transfer to sublingual buprenorphine–naloxone. A conventional transfer is planned; low-dose overlap or micro-induction will not be used. To minimise the risk of precipitated withdrawal, to what maximum daily methadone dose should he first be reduced before buprenorphine is initiated?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — 30 mg daily

The correct answer is E: 30 mg daily. For a conventional transfer, UK prescribing information recommends reducing methadone to no more than 30 mg/day before starting buprenorphine. Buprenorphine has high affinity but only partial agonist activity at the mu-opioid receptor, so it can displace methadone and precipitate withdrawal. Dose reduction alone is insufficient: the first buprenorphine dose should generally be given at least 24 hours after the last methadone dose and only once objective withdrawal is present. Continuing 80 mg or reducing only to 60 mg leaves a greater risk of a difficult transfer. Reducing to 10 mg or 5 mg is not routinely required and may expose the patient to unnecessary withdrawal and treatment disengagement. Alternative micro-induction protocols are outside the conventional transfer specified here.

Reference: Electronic Medicines Compendium, Buprenorphine 2 mg sublingual tablets, Summary of Product Characteristics, sections 4.2 and 4.4, current SmPC. https://www.medicines.org.uk/emc/product/14916/smpc