We would like to thank Dr. Spirko for his comments on our recent publication on the use of ondansetron for vomiting in acute gastroenteritis.
As medicine moves into the 21st century, one questions repeatedly how one practices medicine. With the utility of an evidence-based approach, each of us has had to critically question the treatment plans with varying disease processes. The American Academy of Pediatrics, along with other organizations, has spent time over the past decade publishing practice guidelines derived from both published literature and consensus opinion. The guidelines titled “The Management of Acute Gastroenteritis in Young Children” were published in 1996. They considered 3 specific management issues (1) methods of rehydration, (2) refeeding after rehydration, and (3) the use of antidiarrheal agents. The committee did not evaluate the use of antiemetic drugs. They came to a “consensus opinion” that antiemetic drugs were not needed. They went so far as to say, “Physicians who feel that antiemetic therapy is indicated in a given situation should be aware of potential adverse effects.”
There is a major limitation of the available literature on pharmacologic treatment of nausea and vomiting because of the lack of controlled trials of therapies. As such, the panel was unable to evaluate other than by consensus opinion.
We know that antiemetics act primarily within the central nervous system to suppress nausea and prevent vomiting. Up until our study and a study published in Pediatrics in the same month by Reeves et al, the reluctance and concern related to the use of antiemetics dealt with the significant side effects with such agents. The use of promethazine (Phenergan) is widespread, but usually results in drowsiness, which interferes with the oral rehydration process and the assessment of lethargy. It has a failure rate of 31%, with mild to moderate drowsiness in 71% of patients with acute gastroenteritis. Metoclopramide (Reglan) has also been tried, but the relatively high incidence of side effects such as somnolence, nervousness, irritability, and dystonic reactions, as well as low efficacy, has limited its use.
Choices were limited before the introduction of ondansetron. Ondansetron, a selective 5-HT3 receptor antagonist, marketed as Zofran, is a safe and effective antiemetic, which has been used extensively in pediatric oncology and postoperative patients. No cases of extrapyramidal reactions have been reported in children using ondansetron. The concerns for sedation are not seen with this drug.
We believe that the concern for shifting parental efforts away from oral rehydration therapy toward medication-seeking behaviors is not justified. As reported by Ozuah et al, the vast majority of physicians reported that they always used intravenous therapy for treatment of moderate dehydration, and nearly a third of respondents always used intravenous therapy for mild dehydration. These findings suggest a significant gap between clinical guidelines and current clinical practice. We believe that if this same survey were to be done in 2002, the results would not have changed toward oral rehydration therapy. Most institutions do not push for oral rehydration therapy in the emergency department because of the time commitment. Most parents come with an expectation to receive intravenous fluids. We believe Reeves et al were not pushing for intravenous fluids in all patients but were showing how the additional use of ondansetron noted a cessation of vomiting compared with placebo (71% versus 51%; P=.04). We believe that, with the use of oral ondansetron, oral rehydration therapy would become more attractive to these institutions.
Finally, the observation of no significant difference in the antiemetic effect at 24 and 48 hours was the result of both groups doing comparatively well, rather than a failure of the drug effect. This was touched on in our discussion and was one of the limitations of this study. We used 24-hour historical criteria for assessing severity and, unfortunately, may have included patients who were almost past their vomiting component of the illness. A shorter interval (ie, vomiting >5 times in the past 6 hours or vomiting in the ED) might have eliminated patients for whom an antiemetic was unnecessary. In addition, this would have allowed patients to be targeted earlier in the illness when diarrhea tends not to be significant, thereby reducing this side effect and the revisit rate. We believe that, given the reduction in the admission rate and the use of intravenous fluids in patients receiving ondansetron, it is a justifiable option as a single ED dose in patients with significant vomiting. Caution should be used in patients with significant diarrhea, remembering that the goal is antiemesis and, thereby, encouraging oral rehydration.