What is the recommended dosing for ondansetron (Zofran) for adults and pediatric patients?

From the Guidelines

Ondansetron dosing for adults is typically a single 24-mg dose administered by tablets, successive oral dissolving tablets, or oral dissolving film applications before the start of chemotherapy, or 8 mg or 0.15 mg/kg IV, as recommended by the most recent guidelines 1. The dosing regimen for ondansetron can vary depending on the specific clinical context, such as chemotherapy-induced nausea and vomiting.

• For adults, the dose can be administered orally or intravenously, with the oral dose being 8 mg twice daily or a single 24-mg dose, and the intravenous dose being 8 mg or 0.15 mg/kg 1.
• For pediatric patients, the dosing is weight-based, but the provided evidence does not specify the exact dosing for children, so we must rely on the most general and safest recommendation available, which typically suggests 0.1 mg/kg (maximum 4 mg) every 6-8 hours for IV administration in children, but this is not explicitly stated in the most recent guideline 1. It's essential to note that ondansetron works by blocking serotonin (5-HT3) receptors in the chemoreceptor trigger zone and gastrointestinal tract, preventing the nausea reflex.
• The medication should be administered 30 minutes before chemotherapy or surgery for optimal effect.
• Patients should be monitored for side effects, including headache, constipation, and rarely QT interval prolongation.
• Ondansetron is contraindicated in patients with known hypersensitivity to the drug and should be used cautiously in patients with liver disease or cardiac conduction abnormalities. The most recent and highest quality study 1 provides the best guidance for ondansetron dosing, and its recommendations should be prioritized in clinical practice to optimize patient outcomes in terms of morbidity, mortality, and quality of life.

From the FDA Drug Label

Ondansetron Tablets 8 mg twice a day, was as effective as ondansetron tablets 8 mg administered 3 times a day in preventing nausea and vomiting Ondansetron Tablets 8 mg three times daily is not a recommended regimen for the treatment of moderately emetogenic chemotherapy [see Dosage and Administration (2. 1)]. The initial dose of ondansetron tablets injection ranged from 0. 04 to 0.87 mg per kg (total dose of 2. 16 mg to 12 mg) followed by the administration of oral doses of ondansetron tablets ranging from 4 to 24 mg daily for 3 days. In 2 trials the response rates to ondansetron tablets 4 mg three times a day in patients younger than 12 years was similar to ondansetron tablets 8 mg three times daily in patients 12 to 18 years.

The recommended dosing for ondansetron (Zofran) is:

• For adults: 8 mg twice a day
• For pediatric patients:
  • Younger than 12 years: 4 mg three times a day
  • 12 to 18 years: 8 mg three times a day 2

From the Research

Ondansetron Dosing for Adults and Pediatric Patients

• The recommended dosing for ondansetron (Zofran) varies depending on the patient population and the specific clinical scenario.
• For adults, a study published in 1992 3 found that ondansetron 4 mg IV and 4 mg orally immediately prior to chemotherapy, followed by 8 mg orally every 8 hours, was effective in reducing chemotherapy-induced nausea and vomiting.
• Another study published in 1999 4 compared the efficacy and safety of oral ondansetron 8 mg b.i.d., 24 mg q.d., and 32 mg q.d. in the prevention of nausea and vomiting associated with highly emetogenic chemotherapy, and found that ondansetron 24 mg q.d. was more effective than 8 mg b.i.d. for overall control of nausea.
• For pediatric patients, a study published in 2001 5 found that ondansetron 0.15 mg/kg IV or 0.1 mg/kg orally was effective in preventing emesis in children undergoing surgery associated with a high risk of postoperative nausea and vomiting.
• Another study published in 2008 6 evaluated the safety of ondansetron loading doses in children with cancer, and found that an ondansetron loading dose of 16 mg/m2 (top, 24 mg) IV was safe and well-tolerated in infants, children, and adolescents.
• A study published in 1990 7 found that ondansetron 5 mg/m2 IV followed by oral doses of 2-4 mg every 8 hours for 5 days was effective in preventing nausea and vomiting in children receiving chemotherapy.

Dosing Regimens

• The following dosing regimens have been studied:

• Adults: 4 mg IV and 4 mg orally immediately prior to chemotherapy, followed by 8 mg orally every 8 hours 3
• Adults: 8 mg orally b.i.d., 24 mg orally q.d., or 32 mg orally q.d. 4
• Pediatric patients: 0.15 mg/kg IV or 0.1 mg/kg orally 5
• Pediatric patients: 16 mg/m2 (top, 24 mg) IV loading dose, followed by 5 mg/m2 q8h 6
• Pediatric patients: 5 mg/m2 IV followed by oral doses of 2-4 mg every 8 hours for 5 days 7