FDA Drug Safety Communication

The FDA is informing healthcare professionals and the public that preliminary results from a recently completed clinical study suggest that a 32 mg single intravenous dose of ondansetron (Zofran, ondansetron hydrochloride, and generics) may affect the electrical activity of the heart (QT interval prolongation), which could predispose patients to develop an abnormal and potentially fatal heart rhythm known as torsades de pointes.

GlaxoSmithKline has announced changes to the Zofran drug label to remove the 32 mg single intravenous dose. The updated label will state that ondansetron can continue to be used in adults and children with chemotherapy-induced nausea and vomiting at the lower intravenous dose recommended in the drug label, a dose of 0.15 mg/kg administered every 4 hours for three doses; however, no single intravenous dose should exceed 16 mg. Information from the new clinical study will be included in the updated drug label.

FDA will evaluate the final study results when available, and will work with GSK to explore an alternative single-dose regimen that is both safe and effective for the prevention of chemotherapy-induced nausea and vomiting in adults.

The new information on QT prolongation does not change any of the recommended oral dosing regimens for ondansetron. It also does not change the recommended lower-dose intravenous dosing of ondansetron to prevent postoperative nausea and vomiting.

As part of the ongoing safety review of ondansetron, FDA continues to assess data about the risk of QT prolongation and will update the public when more information becomes available.

View the full FDA Drug Safety Communication on FDA.gov