Experience with ondansetron in chemotherapy- and radiotherapy-induced emesis.

Nausea and vomiting are frequent and severe side-effects of cancer chemotherapy and radiotherapy, and are ranked by patients as one of the worst consequences of such therapy. Ondansetron prevents emesis by blocking the 5-HT3 receptors associated with the vomiting reflex. It has been studied in patients receiving highly emetogenic (cisplatin) chemotherapy, less emetogenic (non-cisplatin) chemotherapy, and radiotherapy. In all studies in these indications, ondansetron was found to be superior to metoclopramide in the control of nausea and emesis over the first 24 h following treatment, when these side-effects are normally most severe. Ondansetron has also been shown to be effective in children and the elderly in the control of cytotoxic-induced emesis. Additional studies have demonstrated that a single intravenous dose of ondansetron (8 mg or 32 mg) is as effective as a continuous infusion schedule, and an 8 mg twice-daily oral schedule is as effective as an 8 mg three times daily oral schedule.