From the FDA Drug Label
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 comparison between 8mg and 4mg of sublingual Zofran (ondansetron) is that similar response rates were observed in pediatric patients younger than 12 years receiving 4mg three times a day and those 12 to 18 years receiving 8mg three times daily, in the context of preventing emesis due to chemotherapy. However, no direct comparison is provided for sublingual administration in the provided drug label. 1
From the Research
Comparison of 8mg and 4mg of Sublingual Zofran (Ondansetron)
- The provided studies do not directly compare the efficacy of 8mg and 4mg of sublingual Zofran (ondansetron) 2, 3, 4, 5, 6.
- However, a study comparing the efficacy of ondansetron orally disintegrating tablets (8 mg and 16 mg) with placebo in patients who developed emesis and/or moderate/severe nausea after receiving fractionated radiotherapy found that there were no statistically significant differences between the two doses of ondansetron 4.
- Another study compared the efficacy and safety of orally administered 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 5.
- There is no direct comparison of 8mg and 4mg of sublingual Zofran (ondansetron) in the provided studies, and therefore, it is not possible to draw a conclusion about the comparison between these two doses 2, 3, 4, 5, 6.
Pharmacokinetics of Ondansetron
- Ondansetron is completely and rapidly absorbed from the gastrointestinal tract after oral administration, and does not accumulate with repeated oral administration 2.
- The bioavailability of ondansetron is about 60% compared with ondansetron administered by infusion over 15 minutes, and is slightly increased when administered after a standard meal 2.
- Ondansetron is widely distributed and binds moderately to plasma proteins, with an elimination half-life of approximately 3.8 hours 2.
Efficacy of Ondansetron
- Ondansetron is an effective and well-tolerated antiemetic, which is used for the prevention of both chemotherapy and radiotherapy-induced emesis and nausea 4.
- Ondansetron orally disintegrating tablets (8 mg and 16 mg) were found to be clinically superior to placebo in treating emesis and nausea successfully over a 12-hour period after taking the medication 4.
- Ondansetron 24 mg q.d. was found to be more effective than 8 mg b.i.d. for overall control of nausea, and at least as effective if not more effective in the control of acute vomiting than 8 mg b.i.d. or 32 mg q.d. 5.