Ondansetron is indicated for:
Ondansetron is a selective 5-HT3 receptor antagonist. While its mechanism of action has not been fully characterized, ondansetron is not a dopamine-receptor antagonist. Serotonin receptors of the 5-HT3 type are present both peripherally on vagal nerve terminals and centrally in the chemoreceptor trigger zone of the area postrema. It is not certain whether ondansetron's antiemetic action is mediated centrally, peripherally, or in both sites. However, cytotoxic chemotherapy appears to be associated with release of serotonin from the enterochromaffin cells of the small intestine.
The most common adverse effects include headache, constipation, diarrhea. In chemotherapy induced nausea and vomiting rash has occurred in approximately 1% of patients receiving Ondansetron. Blurred vision, chest pain with or without ST segment depression, cardiac arrhythmias, hypotension and bradycardia have been rarely reported.
Hypersensitivity reactions have been reported in patients who have exhibited hypersensitivity to other 5-HT3 receptor antagonists. Ondansetron is not a drug that stimulates gastric or intestinal peristalsis. It should not be used instead of nasogastric suction. The use of Ondansetron in patients following abdominal surgery or in patients with chemotherapy-induced nausea and vomiting may mask a progressive ileus and/or gastric distension.
In patients treated with potent inducers of CYP3A4 (i.e Phenytoin, Carbamazepine or Rifampicin), the oral clearance of Ondansetron was increased and Ondansetron blood concentrations were decreased. Data from small studies indicate that Ondansetron may reduce the analgesic effect of tramadol.
In pregnancy: Pregnancy category B. Reproduction studies at daily oral dose up to 10 and 30 mg/kg/day have been performed in animals and have revealed no evidence of impaired fertility harm to the fetus due to Ondansetron. There are, however, no adequate and well-controlled studies in pregnant women. So the drug should be used in pregnancy only if clearly needed.
In lactation: Ondansetron excretes in milk of lactating animals. Caution should be exercised when Ondansetron is administered to nursing mother.
There is no specific antidote for Ondansetron overdose. In addition to the adverse events, hypotension (and faintness) occurred in a patient that took 48 mg of AVONA tablets. In all instances, the events resolved completely.
Ondansetron is contraindicated in patients with known hypersensitivity to the drug.
Prior to IV infusion, dilute in 50 ml dextrose 5% inj or normal saline.
Store in a cool and dry place, protected from light and moisture. For suppository- Store below 25º c.
Pediatric use: Can be given in children 1 month of age and above.
Geriatric use: No dosage adjustment is necessary in the elderly.Dosage adjustment for patients with impaired hepatic function: