From the Guidelines
No, Zyprexa (olanzapine) generally has a lower incidence of QTc prolongation compared to Seroquel (quetiapine). According to the study published in Pediatrics 1, the mean QT prolongation for olanzapine is 2 ms, whereas for quetiapine it is 6 ms. This suggests that Zyprexa has a lower risk of QTc prolongation compared to Seroquel. QTc prolongation is an electrocardiographic finding that can potentially lead to dangerous heart rhythm disturbances such as torsades de pointes. The difference in risk is related to how these medications interact with cardiac ion channels, particularly potassium channels that regulate cardiac repolarization.
- Key factors to consider when choosing between Zyprexa and Seroquel include:
- Pre-existing cardiac conditions
- History of arrhythmias
- Electrolyte abnormalities
- Concomitant use of other QTc-prolonging medications For patients with these risk factors, Zyprexa may be a safer choice due to its lower risk of QTc prolongation. However, individual patient factors should always be considered, and baseline and follow-up ECG monitoring is recommended when using any antipsychotic medication in high-risk patients. Both medications still require appropriate dosing and monitoring, but the risk profile favors Zyprexa regarding QTc effects, as supported by the study 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Comparison of QTc Prolongation between Zyprexa and Seroquel
- The studies provide evidence on the QTc prolongation effects of various antipsychotic medications, including Zyprexa (olanzapine) and Seroquel (quetiapine) 2, 3, 4, 5, 6.
- According to a 2018 meta-analysis, low-quality evidence suggests that olanzapine does not increase the QT interval, while quetiapine is associated with QT prolongation and greater odds of torsades de pointes ventricular tachycardia, especially in cases of drug overdose 4.
- A 2010 study found that antipsychotics such as olanzapine and quetiapine can depress the delayed rectifier potassium current (IKr) in a dose-dependent manner, which may lead to QTc prolongation 6.
- Another study published in 2005 found that combination therapy with an antipsychotic and an antidepressant can cause significant QT prolongation, but it did not specifically compare Zyprexa and Seroquel 5.
- A 2023 review of antipsychotic medications used for delirium symptoms found that olanzapine and quetiapine can cause moderate QTc prolongation, but it did not provide a direct comparison of the two medications 3.
Risk Factors for QTc Prolongation
- The studies identify several risk factors for QTc prolongation, including female gender, concomitant cardiovascular disease, substance abuse, drug interactions, bradychardia, electrolyte disorders, anorexia nervosa, and congenital Long QT syndrome 2, 3, 4, 5, 6.
- Patients taking multiple medications, including antipsychotics and antidepressants, may be at higher risk of QTc prolongation due to potential drug interactions 5, 6.
Monitoring and Management
- The studies suggest that regular ECG monitoring is essential for patients at risk of QTc prolongation, especially those taking antipsychotic medications with a higher risk of QT prolongation 2, 3, 4, 5, 6.
- Clinicians should carefully select psychotropic medications and identify patient risk factors for QTc prolongation to minimize the risk of cardiac arrhythmias 2, 3, 4, 5, 6.