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Citalopram and erythromycin — GPhC CRA MCQ

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ModerateDrug InteractionsCitalopram and erythromycinGPhC CRA

A patient taking citalopram 40 mg daily is prescribed erythromycin and has low magnesium after diarrhoea. What is the most important interaction to flag?

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Correct answer: B — Additive QT prolongation

Both citalopram and erythromycin can prolong QT interval, and low magnesium increases arrhythmia risk. This makes additive qt prolongation the single best answer in this scenario. The other options would either miss the key safety issue, delay appropriate review, or fail to meet the relevant clinical or professional requirement.

Reference: https://www.pharmacyregulation.org/registration-assessment#stage-8-order-52