April 16, 2015 — The label on the anti-nausea drug Zofran carries prominent pregnancy warnings in Canada, but not in the United States.
Prosecutors with the U.S. Department of Justice have accused GlaxoSmithKline (GSK) of illegally marketing Zofran to pregnant women. GSK agreed to a settlement in June 2012, but did not update the label on Zofran to clarify its approved indications. Now, about 1 million pregnant women use Zofran “off-label” to treat morning sickness every year.
The Product Monograph for Zofran in the Canadian market clearly warns that “the safety of ondansetron for use in human pregnancy has not been established,” and “the use of ondansetron in pregnancy is not recommended.”
In contrast, the Prescribing Information for Zofran products for the American market has carried the following pregnancy warning since 1993:
“Pregnancy: Teratogenic Effects: Pregnancy Category B. Reproduction studies have been performed in pregnant rats and rabbits at I.V. doses up to 4 mg/kg per day and have revealed no evidence of impaired fertility or harm to the fetus due to ondansetron. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.”
This warning has not been updated, despite growing evidence linking Zofran and birth defects. Lawsuits claim GSK has failed to adequately warn women, despite receiving over hundreds of reports of women who took Zofran and had a baby with a birth defect.
Furthermore, a growing number of studies have suggested that Zofran might pose risks to a developing baby, especially during the first trimester. One of the largest epidemiological studies, involving 900,000 births in Denmark from 1997-2010, found a 30% increased risk of birth defects and a doubled risk of heart defects associated with Zofran.