Precipitation of ondansetron in alkaline solutions

To the Editor: Ondansetron, a serotonin-receptor antagonist, was approved by the Food and Drug Administration in January 1991 for use in the prevention of nausea and vomiting associated with chemotherapy. Most of the premarketing studies of ondansetron focused on its use in controlling the nausea and vomiting induced by cisplatin or other highly emetic drugs.^1,2 We would like to report a problem with the use of ondansetron to prevent nausea and vomiting caused by the infusion of a large dose of methotrexate (12 g per square meter of body-surface area over a four-hour period). Infusions of high doses of.