From the Guidelines
For patients with a long QT interval, ondansetron and other 5-HT3 receptor antagonists should be avoided as they can further prolong the QT interval, and instead, metoclopramide or prochlorperazine can be considered as alternative antiemetics. According to the study published in Gastroenterology 1, ondansetron is associated with prolonged QTc, making it a less desirable option for patients with pre-existing long QT intervals.
Some key points to consider when selecting an antiemetic for a patient with a long QT interval include:
- Avoiding medications that can further prolong the QT interval, such as ondansetron and other 5-HT3 receptor antagonists 1
- Considering alternative antiemetics like metoclopramide or prochlorperazine, which work by blocking dopamine receptors in the chemoreceptor trigger zone and are less likely to cause QT prolongation
- Monitoring the ECG and maintaining normal electrolyte levels, especially potassium and magnesium, when administering any antiemetic to patients with long QT intervals 1
- Being cautious with medications like promethazine, which may cause sedation, and low-dose haloperidol, which can be effective for severe nausea without significantly affecting the QT interval at these doses
It's also important to note that a baseline ECG should be obtained in all patients and electrolyte abnormalities corrected prior to starting treatment, as recommended in the Journal of the American College of Cardiology 1. Additionally, ECG should be repeated at 7 days after initiation of therapy, according to drug package inserts, and following any dosing changes. Treatment should be stopped if the QTc is > 500 ms on monitoring.
From the Research
Antiemetic Options for Patients with Long QT Interval
When considering antiemetic options for patients with a long QT interval, it is essential to weigh the risks and benefits of each medication.
- Ondansetron, a commonly used antiemetic, has been associated with QT interval prolongation in some studies 2, 3, 4, 5.
- However, other studies have found that the risk of QT prolongation with ondansetron may be lower than previously thought, particularly at lower doses 6.
- The effect of ondansetron on the QT interval can vary depending on the patient population and the presence of other risk factors for torsades de pointes 3.
- Alternative antiemetics, such as metoclopramide or dolasetron, may be considered for patients with a long QT interval, although their safety profiles should also be carefully evaluated 2, 3.
Key Considerations
- Patients with a long QT interval who require antiemetic therapy should be closely monitored for signs of QT prolongation and torsades de pointes 3, 5.
- The risk of QT prolongation with ondansetron may be higher in patients with underlying cardiovascular disease or other risk factors for torsades de pointes 3.
- The benefits of ondansetron therapy should be carefully weighed against the potential risks, particularly in patients with a long QT interval 2, 4.