EFFICACY, DOSE-RESPONSE, AND SAFETY OF ONDANSETRON IN PREVENTION OF POSTOPERATIVE NAUSEA AND VOMITING - A QUANTITATIVE SYSTEMATIC REVIEW OFRANDOMIZED PLACEBO-CONTROLLED TRIALS

Objective: The authors reviewed efficacy and safety data for ondansetr on for preventing postoperative nausea and vomiting (PONV), Methods: S ystematically searched, randomized, controlled trials (obtained throug h MEDLINE, EMBASE, Biological Abstracts, manufacturer's database, manu al searching of journals, and article reference Lists) were analyzed, Relevant end points were prevention of early PONV (within 6 h after su rgery) and late PONV (within 48 h) and adverse effects. Relative benef it and number-needed-to-treat were calculated. The number-needed-to-tr eat indicated how many patients had to be exposed to ondansetron to pr event PONV in one of them who would have vomited or been nauseated had he or she received placebo. Results: Fifty-three trials were found th at had data from 7,177 patients receiving 24 different ondansetron reg imens and from 5,712 controls receiving placebo or no treatment. Avera ge early and late PONV incidences without ondansetron were 40% and 60% , respectively. There was a dose response for oral and intravenous ond ansetron. Best number-needed-to-treat to prevent PONV with the best do cumented regimens was between 5 and 6. This was achieved with an intra venous dose of 8 mg and an oral dose of 16 mg. Antivomiting efficacy w as consistently better than antinausea efficacy, Efficacy in children was poorly documented. Ondansetron significantly increased the risk fo r elevated liver enzymes (number-needed-to-harm was 31) and headache ( number-needed-to-harm was 36). Conclusions: If the risk of PONV is ver y high, for every 100 patients receiving an adequate dose of ondansetr on 20 patients will not vomit who would have vomited had they received placebo, The antinausea effect is less pronounced. Of these 100, thre e will have elevated liver enzymes and three will have a headache who would not have had these adverse effects without the drug.