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Methotrexate pneumonitis — GPhC CRA MCQ

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HardAdverse Drug ReactionsMethotrexate pneumonitisGPhC CRA

A patient receiving methadone maintenance took their last supervised dose three days ago. A new specialist plan proposes starting oral naltrexone today; the urine opioid screen remains positive. Which action is appropriate?

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

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Correct answer: C — Defer naltrexone until opioid freedom is clinically confirmed

Option C is correct: naltrexone can precipitate abrupt severe withdrawal in a person who remains opioid-dependent. The SmPC requires an adequate opioid-free period—at least ten days after methadone—and naltrexone is contraindicated with a positive opioid screen or failed naloxone challenge. Option A mistakes antagonism for detoxification. Option E combines contraindicated therapies. Option B cannot prevent receptor-mediated withdrawal. Option D proposes a non-existent oral substitution and still fails to establish opioid freedom.

Reference: Naltrexone SmPC: https://www.medicines.org.uk/emc/product/8968/smpc