Ondansetron reduces chemotherapy induced nausea and vomiting refractory to standard antiemetics.

Ondansetron, a selective 5HT3 (serotonin) antagonist, was used in patients refractory to standard antiemetics. Seventy-five patients receiving chemotherapy without cisplatin were given ondansetron 4 mg IV and 4 mg orally immediately prior to chemotherapy, then 8 mg orally after six and 12 hours, followed by 8 mg orally eight hourly during days 2-5. Complete control of vomiting occurred in 52 patients (69%) on the first day and 45 patients (60%) on days 2-5. Sixty patients (80%) preferred ondansetron to their previous antiemetics. The efficacy of ondansetron was maintained over multiple chemotherapy cycles. Ondansetron was also given to 16 patients receiving cisplatin chemotherapy. They received 8 mg IV immediately prior to chemotherapy followed by an infusion of 1 mg/hr for 8 hr, with 8 mg orally at the end of the infusion and then 8 mg orally eight hourly during days 2-6. Some control of vomiting (less than = 5 vomits) was achieved in eight patients (50%) on the first day and in 14 patients (87%) on subsequent days. Eight patients (50%) preferred ondansetron to their previous antiemetics. Adverse events with ondansetron were frequent but mild, with constipation and headache being most common. Ondansetron is highly effective in patients refractory to standard antiemetics, especially after noncisplatin chemotherapy.