Zofran (ondansetron): Risk of Abnormal Heart Rhythms

[Guest guest]

From an FDA Safety Alert Published 9/15/11

I'm sure there are more than a few of us on this list using Zofran at least

occasionally for nausea:  

ISSUE:

FDA notified healthcare professionals and patients of an ongoing safety review

and labeling changes for the anti-nausea drug Zofran (ondansetron, ondansetron

hydrochloride and generics). Ondansetron may increase the

risk of developing prolongation of the QT interval of the

electrocardiogram, which can lead to an abnormal and potentially fatal

heart rhythm, including Torsade de Pointes. Patients at particular risk

for developing Torsade de Pointes include those with underlying heart

conditions, such as congenital long QT syndrome, those who are

predisposed to low levels of potassium and magnesium in the blood, and

those taking other medications that lead to QT prolongation.

BACKGROUND:

Zofran (ondansetron) is in a class of

medications called 5-HT3 receptor antagonists. It is used to prevent

nausea and vomiting caused by cancer chemotherapy, radiation therapy and

surgery. FDA is requiring GlaxoKline to conduct a thorough QT

study to determine the degree to which Zofran (ondansetron) may cause QT

interval prolongation.

RECOMMENDATION:

The labels are being revised to

include a warning to avoid use in patients with congenital long QT

syndrome because these patients are at particular risk for Torsade.

Recommendations for ECG monitoring in patients with electrolyte

abnormalities (e.g., hypokalemia or hypomagnesemia), congestive heart

failure, bradyarrhythmias, or in patients taking other medications that

can lead to QT prolongation, are being included in the labels.