Clinical Question: Is ondansetron (Zofran) safe and effective for dehydrated children with gastroenteritis?

Setting: Emergency department

Study Design: Randomized controlled trial (double-blinded)

Allocation: Concealed

Synopsis: Although oral rehydration is the treatment of choice for children with gastroenteritis, it can be a challenge when the child cannot keep anything down. This leads to overuse of intravenous hydration, particularly given the time pressures in the emergency department. The authors considered for inclusion in the study any mildly to moderately dehydrated child who had had at least one episode of diarrhea and one episode of vomiting in the previous four hours. Those with a body weight of less than 17 lb 10 oz (8 kg), who were severely dehydrated using standardized symptoms (e.g., clammy or cool skin, very dry mucosa, no tears, moderate tachycardia, no urine for at least six hours, limp, lethargic), and those with significant comorbidities were excluded.

Of the 243 children asked to enroll, 215 underwent randomization (allocation concealed) to ondansetron or placebo. The dose of ondansetron was 2 mg for children who weighed between 17 lb 10 oz and 33 lb (15 kg), 4 mg for those who weighed 33 lb to 66 lb (30 kg), and 8 mg for those who weighed more than 66 lb. The dose was repeated if children vomited within 15 minutes of taking the medicine. The mean age of the children was 28 months, 57 percent were boys, and they had a mean of nine episodes of vomiting and six episodes of diarrhea in the previous 24 hours. Groups were similar at baseline, and analysis was by intention to treat.

Children receiving ondansetron were less likely to vomit while being given liquids (14 versus 35 percent; P = .001; number needed to treat [NNT] = 5), had fewer vomiting episodes (0.18 versus 0.65; P < .001), and were less likely to require intravenous rehydration (14 versus 31 percent; P = .003; NNT = 5). There was no difference in the number of children requiring hospitalization or the percentage returning to the emergency department. The drug was well tolerated, although there was a mean of 0.9 additional episodes of diarrhea for children who received ondansetron.

Bottom Line: Ondansetron, when given to children who are mildly to moderately dehydrated because of diarrhea and vomiting, improves their ability to comply with oral rehydration and reduces the need for intravenous hydration. (Level of Evidence: 1b)