Summary Safety Review - ZOFRAN (ondansetron) - Assessing the Potential Harm to the Fetus

November 16, 2016

Product

Zofran (ondansetron)

Potential Safety Issue

Harm to the fetus

Key Messages

  • Ondansetron is a prescription drug which is authorized for sale in Canada to manage nausea and vomiting associated with cancer treatment or surgery. Health Canada is aware that ondansetron is prescribed by some clinicians for the treatment of nausea and vomiting related to other conditions, including pregnancy.
  • As part of routine monitoring of ondansetron and because this drug is not authorized for sale in Canada to treat nausea and vomiting during pregnancy, Health Canada carried out a safety review to assess the risk of birth defects.
  • After review of available data, there was not enough information to establish a link between the use of ondansetron during pregnancy and the risk of birth defects. Health Canada will continue to monitor the safety information involving the use of ondansetron during pregnancy.

Overview

Health Canada carried out a safety review to assess the risk of birth defects with the use of ondansetron, as part of routine health product monitoring and because this drug is not authorized for sale in Canada to treat nausea and vomiting during pregnancy. The use of ondansetron during pregnancy is not recommended because its safety has not been established in pregnant women.

Use in Canada

  • Ondansetron is a prescription drug which is authorized for sale in Canada to manage nausea and vomiting associated with cancer treatment or surgery. Health Canada is aware that ondansetron is prescribed by some clinicians for the treatment of nausea and vomiting related to other conditions, including pregnancy.
  • Ondansetron has been marketed in Canada since 1991 under the brand name Zofran. Generic versions of ondansetron are also available. Ondansetron is available for oral and intravenous administration.

Safety Review Findings

  • At the time of the review, Health Canada had received 14 reportsFootnote a of birth defects in the newborn babies of mothers treated with ondansetron. In 4 of these reports, there was not enough information to know at what stage of the pregnancy ondansetron was given. In 2 other reports, ondansetron was given after the organs of the fetus were already developed. In the remaining 8 reports, ondansetron was given to the mother at the stage the organs were developing.
  • In these 8 reports, a link between birth defects and ondansetron could not be ruled out. It was not possible to come to a conclusion whether ondansetron itself caused birth defects because many of the reports lacked information regarding how much and for how long ondansetron was taken. Information about the medical history of the mother, including additional medications she may have been taking, was also lacking. There was no pattern of birth defects.
  • Findings from published scientific studies were not consistent. Moreover, there were concerns with how the studies were designed. The majority of these studies had a number of limitations (e.g., concomitant medications, study design) and conclusions could not be made about the safety of ondansetron use in pregnancy.
  • The findings from animal studies have not established that ondansetron can cause birth defects.

Conclusions and Actions

  • After review of available data, there was not enough information to establish a link between the use of ondansetron during pregnancy and the risk of birth defects. Ondansetron is not authorized for sale in Canada to treat nausea and vomiting in pregnant women, as its safety in that population has not been evaluated.
  • Health Canada is working with the Drug Safety and Effectiveness Network to further investigate the extent of ondansetron use during pregnancy and the risk to the fetus. Health Canada has requested that manufacturers submit information they may have regarding birth defects and use of ondansetron during pregnancy.
  • Health Canada will continue to monitor safety information involving the use of ondansetron as it does for all health products on the Canadian market, to find and study potential harms. Health Canada will take the right and timely action if and when any new health risks are identified.

Additional Information

The analysis that contributed to this safety review included scientific and medical literature, Canadian and international adverse reaction reports and what is known about the use of this drug both in Canada and internationally.

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