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Macrolide and QT prolongation — GPhC CRA MCQ

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ModerateDrug InteractionsMacrolide and QT prolongationGPhC CRA

A patient taking citalopram 40 mg daily and amiodarone presents a prescription for erythromycin. The GP notes a chest infection but no ECG result is available. What is the most important interaction to flag?

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Correct answer: A — The combination may increase QT prolongation risk

Citalopram, amiodarone and erythromycin can contribute to QT interval prolongation, increasing arrhythmia risk. The pharmacist should query the prescription and consider whether an alternative antibiotic is safer. The absence of an ECG result does not remove the concern. The interaction is pharmacodynamic and may also involve metabolic effects with macrolides.

Reference: BNF