Which of the following medications can lengthen the QT interval?

Medications that are known to lengthen the QT interval, particularly antiarrhythmics, can lead to a potentially serious condition known as Torsades de Pointes, which is a type of polymorphic ventricular tachycardia that can result from prolonged QT intervals. Various antiarrhythmic drugs, such as sotalol or dofetilide, are specifically designed to manage dysrhythmias but commonly carry warnings regarding the risk of prolonging the QT interval.

While other medication classes may affect cardiac function, they do not have the same well-documented association with prolonging the QT interval. For instance, NSAIDs are primarily used for pain relief and inflammation and do not significantly impact the QT interval. Similarly, most antibiotics may have varying side effects, but only a few, like certain fluoroquinolones or macrolides, are linked to QT prolongation in specific settings. Beta blockers, on the other hand, are often used in managing arrhythmias and generally have a neutral or even protective effect on the QT interval instead of prolonging it.

Thus, antiarrhythmics are correctly identified as a class of medications that can have a significant effect on the QT interval, making them the appropriate answer in this context.