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Cobalt Chromium Toxicity

How does Zofran cause birth defects?


Birth defects may be caused by drug exposure during early pregnancy. This was first evidenced by the thalidomide tragedy during the post-war era of the 1960’s. Thalidomide was a sleeping pill and tranquilizer marketed as safe for use in pregnant women. Unfortunately, it was anything but safe for the fetus. Severe birth defects secondary to Thalidomide prompted the start of the Food and Drug Administration’s (FDA) drug approval and monitoring systems. According to The Thalidomide Tragedy: Lessons for Drug Safety and Regulation, “They advertised their product as “completely safe” for everyone, including mother and child, “even during pregnancy,” as its developers “could not find a dose high enough to kill a rat.” This is analogous with GlaxoSmithKline and their advertising of Zofran as safe during pregnancy.

Additionally, reproduction studies testing Zofran and it’s teratogenic effects were only performed on pregnant rabbits and rats, much like thalidomide. The Zofran Tablet Prescribing Information states verbatim,  “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.” The ramifications from a lack of testing on human subjects was substantiated with thalidomide. It’s ironic how the thalidomide tragedy catalyzed the FDA’s rigorous drug testing standards yet these standards don’t appear to have been applied to Zofran.

Around the 1960’s, it was discovered thalidomide also alleviated morning sickness. It was subsequently prescribed for off-label use in pregnant patients.  Prescribing drugs for off-label purposes, or purposes other than those for which the drug was approved, is still a common practice in many countries today, including the U.S. In the U.S. today, Zofran is prescribed off-label to alleviate morning sickness in pregnant women. And similar to Thalidomide, it may cause birth defects.

So, how do drugs like Zofran cause birth defects? In the case of Thalidomide, it was discovered that thalidomide caused malformations by interacting with the DNA of the dividing embryonic cells. The research regarding Zofran and it’s interaction with DNA of the developing fetus is still uncertain. However, Zofran has potential to cross the placental barrier. According to Placental Transfer of Ondansetron during Pregnancy, the overall extent of placental transfer, the ratio of fetal tissue to maternal plasma ondansetron (Zofran) concentration was considered significant. In other words, the dosage’s rate of transfer from the mother’s blood stream to the unborn child is significant. The study also suggests Zofran readily passed through the human placenta in the first trimester. A significant amount was found in fetal tissue and amniotic fluid.

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