What are the contraindications for Ondansetron?

From the Guidelines

Ondansetron is contraindicated in patients with a history of prolonged QTc interval.

Contraindications and Precautions

• Baseline ECG is advised before administering ondansetron due to its association with prolonged QTc interval 1.
• The US FDA has expanded warnings in the product labels of ondansetron due to cardiac safety concerns, including the risk of QTc interval prolongation 1.
• A maximum recommended dose of 16 mg of ondansetron i.v. is advised, as the FDA requested withdrawal of ondansetron 32 mg i.v. in 2012 1.
• Caution should be exercised when administering ondansetron to patients with ischemic heart disease, as other medications with similar mechanisms of action are contraindicated in these patients 1.
• It is essential to weigh the benefits and risks of ondansetron in patients with uncontrolled hypertension or peripheral vascular disease, as these conditions may be exacerbated by the medication 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 [see Adverse Reactions (6.2)]. receiving concomitant apomorphine due to the risk of profound hypotension and loss of consciousness.

The contraindications for Ondansetron are:

• Hypersensitivity to ondansetron or any of the components of the formulation
• Concomitant use of apomorphine due to the risk of profound hypotension and loss of consciousness 2

From the Research

Contraindications for Ondansetron

There are no direct contraindications mentioned in the provided studies. However, some studies mention certain conditions where the use of ondansetron may need to be approached with caution:

• Severe hepatic impairment: Ondansetron clearance decreases and half-life increases in patients with severe hepatic insufficiency 3.
• Aging: Clearance decreases with increasing age, whereas volume of distribution remains unchanged 3.
• Pregnancy and lactation: Not mentioned in the provided studies.
• Drug interactions: Ondansetron clearance may be enhanced in patients receiving known hepatic enzyme inducers 3.
• Other conditions: Patients with certain gastrointestinal motility disorders, such as carcinoid syndrome, irritable bowel syndrome, and chronic refractory diarrhea, have shown improvement when treated with ondansetron 4.

Special Considerations

Some studies suggest that ondansetron may be beneficial in patients with certain conditions, such as:

• Nausea and vomiting associated with cancer chemotherapy, radiotherapy, or anesthesia and surgery 5, 4, 6.
• Nausea and vomiting associated with drug overdosage or poisoning, anti-infective or antidepressant therapies, uraemia, or neurological trauma 4.
• Gastrointestinal motility disorders, such as carcinoid syndrome, irritable bowel syndrome, and chronic refractory diarrhea 4.
• Certain pain or CNS-related disorders, such as alcohol dependence, opiate withdrawal, vertigo, cerebellar tremor, and Parkinson's disease treatment-related psychosis 4.

Warnings and Precautions

Some studies mention the following warnings and precautions:

• Ondansetron is generally well-tolerated, but it may cause isolated case reports of extrapyramidal reactions 4.
• Ondansetron does not appear to worsen the symptoms of Parkinson's disease, unlike dopamine receptor-blocking neuroleptics 4.
• The use of ondansetron in critically ill patients may be associated with a decreased risk of mortality, but this requires further exploration 7.