GSK's Zofran arrhythmia risk leads to new label change

With the results of an arrhythmia safety study in, the FDA is having GlaxoSmithKline ($GSK) expand the labeling changes on its Zofran, which is used in chemotherapy for vomiting and nausea.

The clinical study found that a 32mg intravenous dose of the drug "may affect the electrical activity of the heart (QT interval prolongation), which could pre-dispose patients to develop an abnormal and potentially fatal heart rhythm known as Torsades de Pointes," the FDA says in a safety communication.

The notice says the updated label will remove a single 32 mg dosage, leaving in place the lower recommended intravenous dose of 0.15 mg/kg every four hours for three doses with no single intravenous dose to exceed 16 mg. No changes are contemplated at this point for instructions on oral dosing. Currently, oral doses of up to 24 mg are approved, MedPage reports.

In September, the agency had issued a warning that said the drug could induce dangerous and possibly lethal changes in heart rhythms. The label was changed to include "a warning to avoid use in patients with congenital long QT syndrome." The agency also asked GSK to do the study.

Zofran has been in use for some time. In October, South Korea fined GSK $2.6 million for a 2002 agreement with domestic drugmaker Dong-A Pharmaceutical that kept a generic version of Zofran off the market. Dong-A, which was sued by GSK after launching its copycat drug in 1998, was ordered to pay about $1.85 million for its role in the agreement.

- here is the FDA announcement
- read the MedPage story
- here's a Reuters piece

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Korean FTC fines Glaxo, Dong-A in generic Zofran delay