June 29, 2012 — The U.S. Food and Drug Administration (FDA) announced today that they labels on Zofran (ondansetron), a drug that is used to prevent chemotherapy-induced nausea and vomiting. Investigators have determined that a single dose can increase the risk of a deadly heart problem. The manufacturer of Zofran, GlaxoSmithKline, will remove the 32-mg single dose from the label.
The FDA had previously been investigating the risk of heart arrhythmia associated with the drug in collaboration with the drug’s manufacturer. The investigation found that Zofran could prolong the heart’s QT interval (the interval in which the heart recovers before another beat). This increased the risk of a life-threatening type of heart arrhythmia called torsades de pointes, in which the delayed QT interval interferes with the heart’s rhythm so severely that the heart is unable to effectively supply blood to the brain, body, and internal organs.
The updated labels will indicate that adults and children can use Zofran at doses of 0.15 mg/kg every 4 hours for up to three doses, but no single dose should exceed 16 mg. Oral dosages of up to 24 mg are approved by the FDA.
In a statement, the FDA said that they agency will continue to evaluate study data provided by the drug’s manufacturer, and they will work with the drug company to develop an alternative single-dose therapy if possible.
The FDA had previously issued a safety communication on the risk of Zofran heart arrhythmia on September 15, 2011. The FDA announced that the agency was asking GlaxoSmithKline to conduct a safety study, and they would be investigating reports that Zofran had caused changes in heart electrical activity. In the communication, the FDA also recommended that patients who are taking the dug should undergo EKG heart monitoring, especially for patients at risk of heart problems.