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Methadone and citalopram — GPhC CRA MCQ

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HardCNS TherapeuticsMethadone and citalopramGPhC CRA

A 40-year-old man takes methadone oral solution 80mg daily from instalment dispensing and is newly prescribed citalopram 20mg daily. He has a previous ECG showing borderline QT prolongation. What is the most important interaction to flag?

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Correct answer: C — Both medicines can prolong the QT interval and require prescriber review

Methadone and citalopram can each prolong the QT interval, and existing borderline QT prolongation increases concern. The combination should be reviewed for risk factors, alternative antidepressants and monitoring. This is not an absorption interaction. The pharmacist should flag it before supply rather than treating it as routine.

Reference: BNF