What is the effect of Compazine (Prochlorperazine) on QTc interval prolongation?

From the Guidelines

Compazine (prochlorperazine) can prolong the QTc interval, potentially increasing the risk of dangerous heart rhythm abnormalities, and its use should be approached with caution, especially in patients with risk factors for QTc prolongation, as recommended by the European Heart Journal 1. When prescribing Compazine, it's advisable to obtain baseline ECGs in patients with risk factors for QTc prolongation such as heart disease, electrolyte abnormalities, or concurrent use of other QTc-prolonging medications.

• The typical dose for nausea is 5-10 mg orally or intramuscularly every 4-6 hours, with lower doses recommended for elderly patients or those with cardiac risk factors.
• Patients should be monitored for symptoms like dizziness, palpitations, or syncope while on this medication.
• The QTc prolongation occurs because Compazine blocks potassium channels in cardiac cells, delaying ventricular repolarization.
• If a patient develops significant QTc prolongation (>500 ms or an increase of >60 ms from baseline), consider discontinuing the medication or reducing the dose while exploring alternative antiemetics with less cardiac impact, as suggested by the American Heart Association and the American College of Cardiology Foundation 1. According to the acc/aha/esc 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death, removal of the offending agent is indicated in patients with drug-induced LQTS 1. It is also important to note that the risk of QTc prolongation can be increased by certain factors, such as female gender, hypokalemia, bradycardia, and recent conversion from atrial fibrillation, as listed in Table 10 of the acc/aha/esc 2006 guidelines 1. In addition, the use of multiple drugs that prolong the QT interval should be avoided if possible, as recommended by the European Heart Journal 1. Overall, the use of Compazine should be carefully considered and monitored in patients with risk factors for QTc prolongation, and alternative treatments should be explored if possible.

From the Research

Compazine and QTc Interval Prolongation

• There is no direct evidence in the provided studies that specifically mentions Compazine (prochlorperazine) and its effect on the QTc interval.
• However, the studies discuss the importance of monitoring the QTc interval when prescribing medications that may prolong it, as this can increase the risk of torsades de pointes (TdP) 2, 3, 4, 5, 6.
• The studies suggest that certain patient-related risk factors, such as female sex, age, and uncorrected electrolyte disturbances, can increase the risk of QTc interval prolongation 3, 5, 6.
• Additionally, the studies recommend careful monitoring of electrocardiography (EKG) and electrolytes in patients at risk for QT interval prolongation, and provide guidelines for managing drug-induced QT prolongation 4, 5, 6.
• It is essential to consider the potential risk and degree of QT prolongation associated with a proposed drug, as well as co-prescribed medicines that could increase the risk of QT prolongation 6.

Risk Factors for QTc Interval Prolongation

• Hypokalemia, female sex, drug-drug interactions, advancing age, genetic predisposition, hypomagnesemia, heart failure, bradycardia, and corrected QT (QTc) interval prolongation are risk factors for drug-induced TdP 5.
• Many risk factors, including hypokalemia, use of QT-interval-prolonging drugs, and drug interactions are potentially modifiable and should be corrected in persons at risk for QT interval prolongation 5.

Management of Drug-Induced QT Prolongation

• Close monitoring for QTc prolongation is necessary to prevent TdP 5.
• When the QTc interval is 470-500 ms for males, or 480-500 ms for females, or the QTc interval increases 60 ms or more from pretreatment values, dose reduction or discontinuation of the offending drug should be considered where possible, and electrolytes corrected as needed 5.
• If the QTc interval is ≥500 ms, the offending drug should be discontinued, and continuous EKG telemetry monitoring should be performed, or the 12-lead EKG should be repeated every 2-4 hours, until the QT interval has normalized 5.