From the Guidelines
Zofran (ondansetron) is contraindicated in patients with known hypersensitivity to ondansetron or any components of the formulation, as well as in patients taking apomorphine due to the risk of profound hypotension and loss of consciousness. According to the most recent evidence from 1, caution should be exercised in patients with congenital long QT syndrome or those taking medications that can prolong the QT interval, as ondansetron may further increase the risk of potentially life-threatening cardiac arrhythmias. Some key points to consider include:
- Patients with liver dysfunction may require dose adjustments due to decreased clearance of the medication.
- Pregnant women should use ondansetron only if clearly needed, particularly in the first trimester, as some studies suggest a small increased risk of birth defects, though the evidence remains inconclusive, as noted in 1.
- Ondansetron should be used cautiously in patients with electrolyte abnormalities (particularly hypokalemia or hypomagnesemia), congestive heart failure, or bradyarrhythmias, as these conditions may increase the risk of QT prolongation.
- The medication should also be used with caution in patients who have had recent abdominal surgery or those with conditions that might be masked by the antiemetic effect, such as intestinal obstruction. It's essential to weigh the benefits and risks of using ondansetron in each patient, considering their individual health status and medical history, as emphasized in 1 and 1.
From the FDA Drug Label
Patients known to have hypersensitivity (e.g., anaphylaxis) to ondansetron or any components of the formulation. Concomitant use of apomorphine.
The contraindications to Zofran (ondansetron) are:
- Hypersensitivity to ondansetron or any components of the formulation
- Concomitant use of apomorphine due to the risk of profound hypotension and loss of consciousness 2, 2, 3
From the Research
Contraindications to Zofran (Ondansetron)
The following are contraindications to Zofran (ondansetron):
- Hypersensitivity to ondansetron or any of its components 4
- Congenital long QT syndrome 5, 6
- Patients with a history of QT interval prolongation or torsades de pointes 5, 6
- Patients with hypokalemia, hypomagnesemia, or other electrolyte imbalances that may increase the risk of QT interval prolongation 6
- Patients taking other medications that may prolong the QT interval, such as antiarrhythmics, antipsychotics, and certain antibiotics 5, 6
Special Considerations
- Ondansetron should be used with caution in patients with a history of cardiovascular disease, including those with a history of myocardial infarction, arrhythmias, or congestive heart failure 5, 6
- Patients should be monitored for signs and symptoms of QT interval prolongation, including palpitations, syncope, and arrhythmias 5, 6
- The dose of ondansetron should be adjusted according to the patient's renal function and other factors that may affect the drug's pharmacokinetics 5, 7
Warnings and Precautions
- Ondansetron may cause QT interval prolongation, which can increase the risk of torsades de pointes and other arrhythmias 5, 6
- The risk of QT interval prolongation is dose-dependent, with higher doses associated with a greater risk 5, 7
- Patients should be advised to report any symptoms of QT interval prolongation or other adverse effects to their healthcare provider promptly 5, 6