Antiemetic activity of ondansetron in acute gastroenteritis

Background: The mechanism of nausea and vomiting associated with gastroenteritis is unknown. The role of 5-HT3 receptors in emesis associated with gastroenteritis was investigated in paediatric patients. Methods: A randomized, double-blind, placebo-controlled, parallel-group study was conducted in three groups of 12 patients each, receiving either a single i.v. dose of ondansetron (0.3 mg/kg), metoclopramide (0.3 mg/kg) or placebo (sterile saline). Food was restricted and oral rehydration was administered for 4 h. Results: During 0-24 h, the number of emetic episodes experienced was significantly greater (P = 0.048) with placebo (mean = 5) than ondansetron (mean = 2) and the proportion of patients experiencing no emesis was significantly greater (P = 0.039) with ondansetron (58%) than placebo (17%). A numerical difference, in favour of ondansetron, was observed between ondansetron and metoclopramide groups for both of the above parameters. Fewer treatment failures were observed with ondansetron (17%) than placebo (33%) and metoclopramide (42%). More diarrheal episodes were observed in the groups receiving anti-emetic treatment. All three treatments were well tolerated. Conclusions: Ondansetron, a 5HT3 receptor antagonist, was significantly superior to placebo in preventing emesis associated with acute gastroenteritis, in paediatric patients. Therefore, serotonin, acting through 5HT3 receptors, may play a role in this form of emesis.