In a move foreshadowed 6 months ago, the US Food and Drug Administration (FDA) has announced that the 32-mg, single intravenous (IV) dose of the anti-nausea agent Zofran (ondansetron) will no longer be marketed due to the potential for serious cardiac risks. On June 29, 2012, the FDA issued a drug-safety communication stating that the 32-mg, single IV dose of ondansetron should be avoided due to the risk of QT interval prolongation, which can lead to the potentially fatal arrhythmia known as Torsades de Pointes.

The FDA continues to recommend the IV regimen of 0.15 mg/kg, administered every 4 hours for three doses, to prevent chemotherapy-induced nausea and vomiting. If the calculated, weight-based doses were to exceed 16 mg, the potential for prolonged QT interval would be greater. Therefore, no single IV dose should exceed 16 mg. The agency says not enough information is available to support a recommendation of an alternative single IV dose regimen.

In addition to the 0.15 mg/kg, three-dose regimen, oral dosing of ondansetron remains an effective means of preventing nausea and vomiting associated with chemotherapy, the FDA notes.

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The agency is now working with the manufacturers of all 32-mg doses of ondansetron injectable products, both brand and generic, to have these items voluntarily recalled from the market.