Health Canada examines safety of ondansetron used off-label for nausea and vomiting of pregnancy

Health Canada recently carried out a safety review to assess the risk of birth defects with the use of ondansetron (Zofran, generics) to treat nausea and vomiting during pregnancy. In Canada, ondansetron is only authorized for use in the management of nausea and vomiting associated with cancer treatment or surgery.It is not approved for treating nausea and vomiting during pregnancy and is not recommended for this purpose due to the lack of safety data. However, since some physicians prescribe ondansetron to control nausea and vomiting associated with pregnancy, Health Canada conducted a safety review to assess the risk of birth defects.At the time of the review, Health Canada had received 14 reports of birth defects in newborns of mothers treated with ondansetron during pregnancy. Information was insufficient to determine which stage of pregnancy ondansetron was given in four of the cases. In two cases, ondansetron was given after the organs of the fetus were already developed. Ondansetron was given to the mother during the stage of organ development in eight cases.With these eight cases, no specific pattern of birth defects was seen, but a link between the birth defects and ondansetron use could not be ruled out. Several of the reports lacked information regarding the dose and duration of ondansetron use, as well as information on the mother’s medical history and any additional medications she had taken during pregnancy; therefore, it was uncertain whether ondansetron itself caused the birth defects.Published scientific studies examining the safety of ondansetron use in pregnancy have revealed inconsistent results. Most of the studies had a number of limitations (e.g., concomitant medications, study design), which prevented definitive conclusions from being reached. Findings from animal studies have not established that ondansetron can cause birth defects.Based on available data, Health Canada concluded that there is insufficient information to establish a link between ondansetron use during pregnancy and birth defects. Health Canada stresses that ondansetron is not approved to treat nausea and vomiting in pregnant women.Health Canada is collaborating with the Drug Safety and Effectiveness Network to further investigate the extent of ondansetron use during pregnancy and its potential risk to the fetus. Health Canada has also asked manufacturers of ondansetron to submit any data they have on birth defects following the use of ondansetron during pregnancy.ReferenceHealth Canada. Summary safety review - Zofran (ondansetron) - assessing the potential harm to the fetus. November 16, 2016. www.hc-sc.gc.ca/dhp-mps/medeff/reviews-examens/zofran-eng.php (accessed November 24, 2016).

Health Canada examines safety of ondansetron used off-label for nausea and vomiting of pregnancy

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