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Methadone and citalopram QT prolongation — GPhC CRA MCQ

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HardDrug InteractionsMethadone and citalopram QT prolongationGPhC CRA

A 25-year-old man on methadone 80mg daily is prescribed citalopram 20mg daily. He has a history of syncope and his latest ECG shows borderline QT prolongation. What is the most important interaction to flag?

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

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Correct answer: D — Additive QT interval prolongation with methadone and citalopram.

Methadone and citalopram can both prolong the QT interval, and the patient's syncope history plus ECG finding increase concern. The prescriber should review the antidepressant choice and monitoring. The main issue is cardiac risk, not reduced absorption or hypoglycaemia.

Reference: BNF