What is the recommended use and dosage of Ondansetron (Zofran) for preventing nausea and vomiting?

From the Guidelines

Ondansetron (Zofran) is recommended at a dose of 16-24 mg PO once or 8-16 mg IV once for preventing nausea and vomiting, as per the most recent guidelines 1.

Key Considerations

• The dosage may vary depending on the specific context, such as chemotherapy-induced nausea, where a higher initial dose may be given before treatment.
• Ondansetron works by blocking serotonin receptors in the brain and gut that trigger nausea and vomiting.
• Common side effects include headache, constipation, and dizziness.
• Patients should take the medication exactly as prescribed and inform their doctor of any other medications they're taking to avoid interactions.

Administration and Forms

• The medication is available in various forms, including tablets, oral dissolving tablets, and liquid, making it suitable for different patient needs.
• For maximum effectiveness, maintain proper hydration while using this medication.

Clinical Guidelines

• The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Antiemesis provide recommendations for antiemetic prophylaxis according to the emetogenic potential of antitumor therapies 1.
• Other guidelines, such as those from the European Society for Medical Oncology (ESMO), also recommend ondansetron for preventing chemotherapy-induced nausea and vomiting 1.

Special Considerations

• For radiation-induced nausea and/or vomiting, ondansetron may be used at a dose of 8 mg, 2-3 times daily, with or without oral dexamethasone 1.
• The dosage and administration of ondansetron may need to be adjusted based on individual patient factors, such as age, sex, and prior chemotherapy.

From the FDA Drug Label

14 CLINICAL STUDIES 14. 1 Prevention of Chemotherapy-Induced Nausea and Vomiting

Highly Emetogenic Chemotherapy In 2 randomized, double-blind, monotherapy trials, a single 24-mg oral dose of ondansetron was superior to a relevant historical placebo control in the prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m2 A total of 66% of patients in the ondansetron 24-mg once-a-day group, 55% in the ondansetron 8‑mg twice-a-day group, and 55% in the ondansetron 32‑mg once-a-day group, completed the 24-hour trial period with 0 emetic episodes and no rescue antiemetic medications, the primary endpoint of efficacy Dosage regimens of ondansetron 8 mg twice daily and 32 mg once daily are not recommended for the prevention of nausea and vomiting associated with highly emetogenic chemotherapy [see Dosage and Administration (2. 1)]. Moderately Emetogenic Chemotherapy A randomized, placebo-controlled, double‑blind trial was conducted in the US in 67 patients receiving a cyclophosphamide‑based chemotherapy regimen containing doxorubicin The first 8-mg dose of ondansetron was administered 30 minutes before the start of chemotherapy, with a subsequent dose 8 hours after the first dose, followed by 8 mg of ondansetron twice a day for 2 days after the completion of chemotherapy.

The recommended use and dosage of Ondansetron (Zofran) for preventing nausea and vomiting are:

• A single 24-mg oral dose for highly emetogenic chemotherapy, administered 30 minutes prior to chemotherapy.
• For moderately emetogenic chemotherapy, 8 mg of ondansetron can be administered 30 minutes before the start of chemotherapy, with a subsequent dose 8 hours after the first dose, followed by 8 mg of ondansetron twice a day for 2 days after the completion of chemotherapy. 2

From the Research

Recommended Use of Ondansetron

• Ondansetron is a selective 5-HT3 receptor antagonist used as an antiemetic to prevent nausea and vomiting associated with cancer chemotherapy, radiotherapy, and postoperative nausea and vomiting 3.
• It is effective in preventing nausea and vomiting caused by highly emetogenic chemotherapy, and its combination with dexamethasone is more effective than ondansetron monotherapy in controlling emesis 3, 4.

Dosage of Ondansetron

• The recommended dosage of ondansetron for preventing nausea and vomiting associated with chemotherapy is 8 mg twice daily for 3 days, with the first dose administered 30 minutes before the initiation of chemotherapy 5.
• For preventing postoperative nausea and vomiting, ondansetron can be administered as a single dose of 4-8 mg, 30 minutes to 1 hour before surgery 6.
• However, the US Food and Drug Administration (FDA) has issued a warning for ondansetron due to a potential for prolongation of the QT interval, and the dose of 32 mg i.v. (or several doses equivalent to this) is of concern 7.

Efficacy and Safety of Ondansetron

• Ondansetron has been shown to be effective in preventing nausea and vomiting associated with moderately emetogenic cancer chemotherapy, with 61% of patients treated with ondansetron having no emetic episodes during the 3-day study period 5.
• The most common adverse events associated with ondansetron are headache and constipation, with an overall incidence of adverse events of 36% 3.
• Ondansetron has been shown to be more effective than placebo in preventing postoperative nausea and vomiting, but its use in this setting may be limited due to its high cost 6.