June 29, 2012 — Today the U.S. Food and Drug Administration (FDA) announced the conclusion of a safety study regarding Zofran (ondansetron), an anti-nausea and vomiting drug given to people who are undergoing chemotherapy.
The FDA had required the drug’s manufacturer, GlaxoSmithKline, to begin a safety study in 2011 regarding the link between Zofran and deadly heart arrhythmias. The label on the drug will be updated to warn that the 32-mg single dose of Zofran can increase the risk of arrhythmias.
An FDA review of medical literature found that Zofran was associated with heart problems. The reviewers found that the drug could affect the heart’s electrical activity by prolonging the QT interval (the time in which the heart recovers between beats). A very long QT interval can cause tordsades de pointes, a life-threatening heart arrhythmia in which the heart is unable to pump effectively, and therefore cannot supply the body with blood.
The updated labels on Zofran will indicate that dosages should not exceed 0.15 mg/kg every 4 hours, up to three doses. The FDA has approved oral doses up to 24-mg, but no single oral dose should exceed 16-mg. The drug manufacturer will no longer sell 32-mg single dosages of Zofran due to the risk of heart arrhythmias.
The FDA said that they will continue to review data from the manufacturer’s safety study. Furthermore, they will continue to work on developing a safe single-dose therapy.
Due to concern over the safety of Zofran, on September 15, 2011, the FDA published a safety communication. They warned that they were investigating a possible link between Zofran and changes to the heart’s electrical activity, and furthermore, they were requiring the drug’s manufacturer to conduct a safety study. The FDA advised that doctors should monitor their Zofran patients with EKG tests, especially patients who were at high risk of having heart problems.