ONDANSETRON - AN UPDATE OF ITS THERAPEUTIC USE IN CHEMOTHERAPY-INDUCED AND POSTOPERATIVE NAUSEA AND VOMITING

Ondansetron is a selective 5-HT3 receptor antagonist which has previou sly been reported in the Journal to be a promising new agent for use a s prophylaxis against nausea and vomiting caused by chemotherapy and r adiotherapy. Since the publication of this original review, further st udies have been published that show ondansetron to be an effective ant iemetic agent in patients receiving chemotherapy and radiotherapy. Sev eral studies have shown ondansetron to be a more effective antiemetic agent than high-dose metoclopramide in patients with emesis induced by high- and low-dose cisplatin treatment, and noncisplatin chemotherapy -induced emesis. The drug as mono-therapy does not appear to offer any advantage over alternative therapies against delayed high-dose cispla tin-induced nausea and vomiting; however, extremely limited data sugge st that ondansetron plus dexamethasone may be useful in this indicatio n. Trials have shown combination therapy with ondansetron and dexameth asone to be significantly more effective than both ondansetron monothe rapy and a standard antiemetic regimen comprising metoclopramide, dexa methasone and diphenhydramine against acute high-dose cis-platin-induc ed emesis. Results from a number of small scale trials suggest that on dansetron may be an effective treatment for chemotherapy-induced emesi s refractory to conventional antiemetic therapy. Ondansetron also appe ars to be more effective against refractory emesis induced by noncispl atin chemotherapy than that induced by cisplatin chemotherapy. Several trials have shown ondansetron to be more effective than placebo as pr ophylaxis against postoperative nausea and vomiting; a further trial h as shown single-dose ondansetron to be significantly more effective th an single-dose droperidol or metoclopramide in this indication. In add ition, several trials have shown ondansetron to be more effective than placebo as treatment for nausea and vomiting that has commenced posto peratively. The overall incidence of adverse events in ondansetron rec ipients during chemotherapy-induced emesis studies was 36%. Headache a nd constipation are the most common adverse events during ondansetron therapy. Thus, recent data affirms the efficacy of ondansetron in the treatment of acute chemotherapy-induced nausea and vomiting and shows it to be especially efficacious when combined with dexamethasone. It a ppears that the drug will also have a substantial role in the prophyla xis and treatment of postoperative nausea and vomiting.