From the Guidelines
Contraindications to scheduled ondansetron (Zofran) include hypersensitivity to ondansetron or other 5-HT3 receptor antagonists.
Key Considerations
- A baseline ECG is advised for patients taking ondansetron due to its association with prolonged QTc 1.
- Patients with a history of ischemic heart disease, stroke, peripheral vascular disease, or uncontrolled hypertension should exercise caution when taking ondansetron, although it is not explicitly contraindicated in these conditions 1.
Important Contraindications
- Congenital long QT syndrome is a contraindication to ondansetron due to the risk of torsades de pointes.
- Patients taking medications that prolong the QT interval, such as quinolone antibiotics or antipsychotics, should avoid scheduled ondansetron due to the potential for increased risk of torsades de pointes.
Additional Precautions
- Ondansetron should be used with caution in patients with a history of cardiac arrhythmias or those taking medications that affect cardiac conduction 1.
From the FDA Drug Label
Ondansetron tablets are contraindicated in patients: known to have hypersensitivity (e. g., anaphylaxis) to ondansetron or any of the components of the formulation receiving concomitant apomorphine due to the risk of profound hypotension and loss of consciousness.
The contraindications to scheduled ondansetron (Zofran) 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
From the Research
Contraindications to Scheduled Ondansetron (Zofran)
The following are potential contraindications to scheduled ondansetron (Zofran):
- Prolonged QT interval, as ondansetron can further prolong the QT interval and increase the risk of ventricular arrhythmias, particularly torsades de pointes 3, 4
- Cardiovascular disease, such as heart failure or acute coronary syndromes, with additional risk factors for torsades de pointes, as ondansetron may significantly increase the QTc interval in these patients 4
- Concurrent use of other medications that prolong the QT interval, as this may increase the risk of ventricular arrhythmias 3, 4
Patient Characteristics that Increase Susceptibility to Contraindications
The following patient characteristics may increase susceptibility to contraindications:
- Abnormal QT interval at baseline 3
- Risk factors for torsades de pointes, such as cardiovascular disease, electrolyte imbalances, or concurrent use of other medications that prolong the QT interval 3, 4
- Diabetic patients, as they may be at increased risk of QTc prolongation 5
Important Considerations
It is essential to carefully evaluate the risks and benefits of scheduled ondansetron in patients with potential contraindications and to monitor them closely for signs of ventricular arrhythmias, particularly torsades de pointes. Patients who are at high risk for torsades de pointes and receiving ondansetron should be followed via telemetry when admitted to hospital 4.