Ondansetron expedites oral rehydration in gastroenteritis

A randomized trial in children with gastroenteritis and dehydration showed that a single dose of oral ondansetron reduces vomiting, which facilitates oral rehydration and decreases the likelihood that intravenous fluids will be required. Investigators compared the effects of an orally disintegrating ondansetron tablet with placebo in 215 children between 6 months and 10 years of age who were treated in a pediatric ED for gastroenteritis and dehydration.

The weight-based dose of ondansetron was 2 mg for children 8 to 15 kg; 4 mg for children more than 15 kg and as much as 30 kg; and 8 mg for children more than 30 kg. Children who vomited within 15 minutes after receiving the medication or placebo received a second dose. Fifteen minutes after administration, one-hour intense oral rehydration began, and was continued until the child was admitted or sent home.

Of children who received ondansetron, 14% vomited while receiving oral rehydration, compared with 35% of children who received placebo. The mean number of episodes of vomiting also was significantly lower among children who received ondansetron. Among children who did not vomit, IV hydration was administered less often in the ondansetron group (5% of subjects) than in the placebo group (17%).

Commentary Five children would need to be treated to prevent one child from vomiting during oral rehydration. For every six children treated, one would avoid IV rehydration. Ondansetron is not cheap-but neither is IV rehydration. You may want to give this regimen a try during the next outbreak of gastroenteritis in your community.