A review of the potential for prolongation of the QT interval associated with ondansetron has resulted in some "interim" changes to the drug’s label, the Food and Drug Administration announced on Sept. 15.
In a drug safety announcement, the FDA said that the agency conducted a review of all the available information on the risk of QT prolongation with ondansetron and is making the changes, which include recommending against the use of the antinausea drug in patients with congenital long QT syndrome.
Used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery, ondansetron is a 5-hydroxytryptamine-3 (5-HT3) receptor antagonist marketed as Zofran by GlaxoSmithKline, and is available in generic formulations. Information on the potential for QT prolongation is already included in the label, and QT interval prolongation with ondansetron has been reported in the medical literature, according to the announcement.
But the label will now also recommend ECG monitoring in patients who are treated with ondansetron and have an electrolyte abnormality, congestive heart failure, or bradyarrhythmias, and in patients taking other medications that prolong the QT interval – who are at an increased risk of developing torsades de pointes. QT prolongation can result in the abnormal and potentially fatal heart rhythm torsades de pointes, which has also been reported in patients taking ondansetron, the FDA statement points out.
Patients taking ondansetron should also be advised to contact a health care professional immediately, if they develop signs and symptoms of an abnormal heart rate or rhythm, the statement says.
GlaxoSmithKline is being required by the FDA to conduct a study that will evaluate the potential for ondansetron to prolong the QT interval; results are expected in the summer of 2012. The safety review is ongoing, and "the FDA will continue to assess all available data supporting the safety and effectiveness of ondansetron and will update the public when more information becomes available," the statement said.
The notice is available online. Serious adverse events associated with ondansetron should be reported to the FDA’s MedWatch program at 800-332-1088.