Which medication is most associated with QT prolongation risk when treating bipolar disorder?

Which medication is most associated with QT prolongation risk when treating bipolar disorder?

• A. Lithium
• B. Lamotrigine
• C. Quetiapine
• D. Haloperidol

Answer: (D)

QT prolongation signals delayed ventricular repolarization, which can lead to dangerous arrhythmias like torsades de pointes. Among bipolar meds, haloperidol carries the strongest association with this risk. This is especially true at higher doses or with IV administration, and when used with other QT-prolonging drugs or in patients with electrolyte disturbances. The mechanism involves blocking cardiac IKr potassium channels, which slows repolarization. Lithium and lamotrigine do not meaningfully affect the QT interval, and while quetiapine can prolong QT modestly, haloperidol has the highest risk among these options.

QT prolongation signals delayed ventricular repolarization, which can lead to dangerous arrhythmias like torsades de pointes. Among bipolar meds, haloperidol carries the strongest association with this risk. This is especially true at higher doses or with IV administration, and when used with other QT-prolonging drugs or in patients with electrolyte disturbances. The mechanism involves blocking cardiac IKr potassium channels, which slows repolarization. Lithium and lamotrigine do not meaningfully affect the QT interval, and while quetiapine can prolong QT modestly, haloperidol has the highest risk among these options.