Dosage Forms. Tablet: 4 mg, 8 mg, 24 mg; Tablet, Dispersable: 4 mg, 8 mg; Solution: 4 mg/5 mL; Film: 4 mg, 8 mg
Common FDA Label Indication, Dosing, and Titration.
1. Chemotherapy-induced nausea and vomiting, highly emetogenic chemotherapy: 24 mg po 30 min prior to the start of chemotherapy
2. Chemotherapy-induced nausea and vomiting, moderately emetogenic chemotherapy: Adults and Children >12 y, 8 mg po 30 min prior to chemotherapy and repeated in 8 h, then 8 mg po q12h for 1-2 d post chemotherapy; Children 4-11 y, 4 mg po 30 min prior to chemotherapy, repeated 4 and 8 h after the first dose, then q8h for 1-2 d post chemotherapy
3. Postoperative nausea and vomiting: 16 mg po 1 h before anesthesia induction
4. Radiation-induced nausea and vomiting: 8 mg po 1-2 h prior to radiotherapy and q8h after first dose of radiation on each day radiotherapy
1. Gastroenteritis, vomiting: 2 mg po q8h prn for children 8-15 kg, 4 mg po q8h prn for children 15-30 kg, and 8 mg po q8h prn for children >30 kg
MOA. Ondansetron is a selective 5-HT3 receptor antagonist. Serotonin receptors of the 5-HT3 type are present both peripherally and centrally in the chemoreceptor trigger zone of the area postrema. Cytotoxic chemotherapy releases serotonin from the enterochromaffin cells of the small intestine, initiating the vomiting reflex.
Drug Characteristics: Ondansetron
Medication Safety Issues: Ondansetron
Drug Interactions: Ondansetron
Adverse Reactions: Ondansetron
Efficacy Monitoring Parameters. Reduction in nausea and vomiting.
Toxicity Monitoring Parameters. Heart palpitations, shortness of breath, severe rash.
Key Patient Counseling Points. Dry hands before handling disintegrating tablet. Do not open the blister pack that contains the tablet until you are ready to take it. Do not push the oral disintegrating tablet through the foil. Place tablet in mouth, allow to melt, swallow, or drink water.
Clinical Pearls. Tablets, disintegrating tablets, and solution are bioequivalent and are dosed interchangeably. 5-HT3 receptor antagonists are often combined with dexamethasone and aprepitant. Also available in injectable formulation; 32 mg injectable formulation removed from market due to high risk of QT prolongation.