Which of the following antipsychotics is associated with a risk of QT prolongation?

Thioridazine is known to be associated with the risk of QT prolongation due to its pharmacological profile. This antipsychotic, belonging to the phenothiazine class, has a specific mechanism of action that can interfere with cardiac repolarization. The prolongation of the QT interval can lead to serious arrhythmias, including Torsades de Pointes, which can be life-threatening.

Patients taking thioridazine require careful monitoring of their cardiac status, especially if they have other risk factors for QT prolongation, such as concurrent use of other medications that affect cardiac conduction, electrolyte imbalances, or a personal or family history of cardiac arrhythmias.

In contrast, fluoxetine, which is a selective serotonin reuptake inhibitor (SSRI) primarily used for depression and anxiety, has a much lower association with QT prolongation. Aripiprazole, an atypical antipsychotic, also has a minimal risk in this regard. Buspirone, an anxiolytic used mainly for generalized anxiety disorder, is not typically associated with QT prolongation either. Thus, the pronounced effect on the QT interval makes thioridazine the relevant answer in this context.