New Study Explores Transplacental Transfer of Zofran

A recent study published in the medical journal Clinical Pharmacology & Therapeutics evaluated the possibility that the anti-nausea drug, Zofran (ondansetron) might be used to treat neonatal abstinence syndrome.

In doing so, the researchers also assessed the possible transfer of the drug from mother to fetus via the placenta. Zofran is a medication manufactured by GlaxoSmithKline (GSK) that is approved for purpose of treating nausea and vomiting in patients who are undergoing chemotherapy and those who are having surgery. However, it has also been prescribed for off-label use, such as for pregnant women who are experiencing morning sickness.

Results suggest rapid transplacental transfer

Researchers from the Royal Free Hospital in London, the University of Colorado, and Stanford University studied plasma samples taken from 40 pregnant women and 20 women who were not pregnant. They also studied samples taken from umbilical cord blood and from the infants themselves following their births. The results of the study suggest that when Zofran is used during pregnancy, it is “characterized by rapid transplacental transfer and longer elimination half-life in neonates compared to their mother,” according to the study.

Researchers aren’t the first to evaluate Zofran

This latest study published in Clinical Pharmacology & Therapeutics adds further clinical data to the growing body of research regarding the anti-nausea medication. A 2006 observational study that was published in the medical journal Clinical Pharmacokinetics also evaluated the possibility of transfer of the drug through the placenta to the fetus. In this observational study, 41 women who were expecting to undergo surgical abortion in the first trimester took three doses of Zofran while still pregnant. All of the doses consisted of 8 mg of the drug. The researchers then collected fetal tissue, amniotic fluid, maternal blood, and coelomic fluid. After analyzing these samples via liquid chromatography mass spectrometry, the researchers concluded that Zofran was present in all of the samples. According to the study, “drug concentration in fetal tissue was significantly higher than that in the amniotic fluid and similar to that in the coelomic fluid.”

The results suggest that Zofran can cross to the fetus via the placenta. However, neither of these transplacental transfer studies evaluated the possible risks of birth defects from Zofran. They only analyzed the transfer of the drug. Furthermore, the researchers noted that additional studies into this area were needed.

Lawsuits filed over Zofran birth defect risk

More conclusive research into the possible risks of Zofran to both mother and fetus are needed. Currently, a handful of Zofran lawsuits filed against GSK allege that after the plaintiffs took the medication during pregnancy, their children were born with birth defects, including heart malformations. Although these allegations are troubling, they are not proof of a definitive link between the Zofran and an increase in the risk of birth defects.

Another study published in the journal Clinical and Molecular Teratology evaluated the potential risks of various drugs to the fetus. In this 2011 study, the researchers concluded that there was a possibility that Zofran increased the risk of birth defects; however, the authors noted that this “could be chance findings (and) warrant further investigation.”

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