Main adverse drug reaction of macrolides?

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Multiple Choice

Main adverse drug reaction of macrolides?

QT prolongation is the main adverse reaction associated with macrolides and can lead to torsades de pointes, a potentially life‑threatening arrhythmia. This risk comes from macrolides blocking cardiac potassium channels (the hERG channels), which delays repolarization and lengthens the QT interval on the ECG. While gastrointestinal upset is common with macrolides, the potential for dangerous heart rhythm disturbances is the key safety concern, especially in patients taking other QT‑prolonging drugs or who have electrolyte disturbances or preexisting long QT. Erythromycin and clarithromycin tend to have higher proarrhythmic potential, whereas azithromycin has a comparatively lower risk but is not free of it. In practice, consider coexisting medications and electrolyte status, and monitor or avoid QT‑prolonging combinations in high‑risk patients.

QT prolongation is the main adverse reaction associated with macrolides and can lead to torsades de pointes, a potentially life‑threatening arrhythmia. This risk comes from macrolides blocking cardiac potassium channels (the hERG channels), which delays repolarization and lengthens the QT interval on the ECG. While gastrointestinal upset is common with macrolides, the potential for dangerous heart rhythm disturbances is the key safety concern, especially in patients taking other QT‑prolonging drugs or who have electrolyte disturbances or preexisting long QT. Erythromycin and clarithromycin tend to have higher proarrhythmic potential, whereas azithromycin has a comparatively lower risk but is not free of it. In practice, consider coexisting medications and electrolyte status, and monitor or avoid QT‑prolonging combinations in high‑risk patients.

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