Clinical safety of ondansetron

The safety of intravenous (IV) and oral ondansetron has been evaluated in over 7,000 cancer patients in world-wide clinical trials. In adult patients receiving single-day chemotherapy, the incidence of adverse events was 45% with IV ondansetron (n = 317) and 59% with metoclopramide (n = 279). Headache occurred in 17% of ondansetron patients and 10% of metoclopramide patients, whereas diarrhea symptoms were reported in 15% of the former and 29% of the latter. The incidence and types of adverse events were similar following three 0.15 mg/kg IV ondansetron doses and 8- or 32-mg single IV doses. There was a slight increase in the incidence of headache following a single 32-mg dose (25%) compared with a single 8-mg dose (18%) or three 0.15 mg/kg doses (18%). The safety profile of oral ondansetron was similar to that of the IV formulation. Following an 8-mg oral dose administered three times a day for 3 days, the most frequently reported adverse events were headache (21%), constipation (7%), and abdominal pain (5%). In a group of 209 pediatric patients receiving chemotherapy, the incidence of adverse events following IV and oral ondansetron was 19%. The most commonly reported adverse event was headache (4%). In comparative clinical trials, extrapyramidal symptoms were reported in 5% of the metoclopramide patients but none of the ondansetron patients. In open-label trials, two patients who received ondansetron reported symptoms consistent with, but not diagnostic of, extrapyramidal reactions. The incidence of vascular occlusive events and seizure disorders was identical for ondansetron and comparative agents. Serum transaminase values increased significantly in 6% to 8% of ondansetron patients and 2% of metoclopramide patients who received cisplatin. There was no apparent relationship between the dose of ondansetron administered and the incidence of increased transaminase abnormalities. However, there was an apparent relationship between the dose of cisplatin administered and the incidence of transaminase abnormalities. In patients who received non-cisplatin chemotherapy, there was no difference in serum transaminase values between oral ondansetron and placebo. These data demonstrate that ondansetron is better tolerated than metoclopramide and is safe for IV and oral administration to patients receiving chemotherapy. In addition, ondansetron is well tolerated when administered as a single 32-mg infusion over 15 minutes.