December 5, 2012 – The 32-mg dose of the widely-prescribed anti-nausea drug Zofran (generic: ondansetron) has been pulled off the market due to numerous reports of serious cardiac problems in users, the U.S. Food & Drug Administration (FDA) reported yesterday. Earlier this year, the FDA issued a press release warning the public that the 32-mg dose of Zofran had been linked to an increased risk of QT interval prolongation, which can lead to torsades de pointes, a potentially fatal heart arrhythmia. Manufactured and marketed by GlaxoSmithKline (GSK), Zofran is approved for preventing chemotherapy-induced nausea and vomiting, and is administered as a single intravenous dose.
What’s the problem?
Zofran is designed to block the actions of chemicals in the body that can trigger nausea and vomiting. These reactions are complex biological processes that involve a number of chemicals and body parts, including the brain and small intestine. Zofran is designed to block serotonin – a neurotransmitter produced by the body that is associated with upset stomach and vomiting – at a specific type of receptor known as the 5-HT3 receptor.
New research ordered by the FDA found a maximum mean difference in QTcF (a formula which takes into account the shortening of the QT interval across a range of rates) of 20 milliseconds after the 32-mg IV dose. An IV dose of 8 mg, on the other hand, led to a mean maximum QTcF difference of 6 milliseconds.
The FDA stated that all remaining lots of the 32-mg version of Zofran should be removed from the market by early 2013, and that the recall should not result in a shortage of the drug, since the 32-mg dose represents a very small fraction of the current market. The 0.15 mg intravenous regimen of Zofran continues to be recommended to prevent chemotherapy-induced nausea and vomiting. Additionally, the FDA has determined that oral dosing of Zofran remains effective for these purposes.
Zofran Side Effects
In addition to the risk of potentially fatal heart rhythm abnormalities, Zofran has also been linked to a number of more moderate side effects including:
- lethargy (fatigue)
- low oxygen levels
- gynecological disorders
- anxiety or agitation
- difficulty emptying the bladder
Interested in learning more? Click here if you’d like more information about Zofran side effects from the Mayo Clinic.