Health Canada warns against use of highest dose of anti-nausea IV drug Zofran

Health officials in Canada are warning about potentially life-threatening side effects associated with an anti-nausea drug.

Zofran, a drug that’s administered at 32 milligrams intravenously, should be avoided altogether, Health Canada is warning. The agency is warning that the drug administered at this dose can impact a patient’s QT interval, a measure of a heart’s electrical activity. Zofran at this dose can prolong a patient’s QT interval. This condition can lead to dizziness and cause an irregular heartbeat. A report from Canada Broadcasting Corp. adds that QT interval can also cause fainting and death. QT prolongation could also result in a fatal condition known as Torsades de Pointes.

Considering these dangerous side effects, Health Canada has mandated that no higher dose than 16 milligrams of Zofran be administered to patients.

This drug, at 32 milligrams, is dispensed to patients who undergo chemotherapy in the treatment of cancer and to post-operative patients to prevent nausea and vomiting. In addition to its brand name form, Zofran is also known as ondansetron hydrochloride dihydrate or ondansetron in generic form.

Health Canada’s warning does not include any dosing instruction changes for lower doses of Zofran, including those who are given the drug orally and for children who receive the drug both orally and intravenously.

If a person is taking Zofran and feels faint, dizzy, or notices they’ve developed an abnormal heartbeat, they should immediately alert their prescribing physicians to avoid potentially life-threatening side effects.

Earlier this year, the domestic Food and Drug Administration added warnings about the risks of QT prolongation to safety information included with Zofran. The FDA, at the time, made the judgement to update safety labels on Zofran after reviewing initial data from a clinical trial of the drug. When this study was completed, the FDA said it would work with the makers of Zofran, GlaxoSmithKline, to develop a heart-safe dose of Zofran that would be effective at reducing nausea among people undergoing chemotherapy, radiation therapy, or those who’ve just undergone surgery.

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