11 October 2016

What Is Zofran’s FDA Pregnancy Category?

Nearly 300 families have sued GlaxoSmithKline, claiming the company’s potent anti-nausea drug Zofran causes birth defects. As the growing litigation develops, more and more women have become aware of troubling studies that link Zofran – now America’s most popular morning sickness drug – to congenital abnormalities like cleft palate and congenital heart defects.

Anti-Nausea Drug Pregnancy Classification

Throughout the debate over Zofran’s potential pregnancy risks, the US Food & Drug Administration has remained silent. The agency hasn’t issued a recall, or instructed obstetricians to stop prescribing the drug to their pregnant patients. Nor has the FDA changed Zofran’s Pregnancy Category.

Pills Spilling Out Of Bottle

In fact, the US Food & Drug Administration no longer uses a grading system to classify drugs based on their pregnancy risks. The federal agency dropped its letter-based risk classification scheme in 2015, citing patient and doctor confusion. Instead of letter grades, the FDA now requires detailed descriptions of a drug’s pregnancy risks.

Pregnancy Category Prior To 2015

Between 1992 and 2015, the US Food & Drug Administration classified Zofran in Pregnancy Category B:

“Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women.”

That classification placed Zofran in the over-crowded field of drugs that have never been studied in pregnant women. Pregnant women are usually excluded from clinical trials for ethical reasons, so we rarely have a good understanding of which drugs can cause birth defects until a medication has reached the open market. Where studies in pregnant animals are concerned, Pregnancy Category B says that these studies have found no evidence of fetal harm.

That doesn’t sound like a very good reason to start taking Zofran during pregnancy, though. In fact, some experts have come out strong against the anti-nausea drug’s rampant prescription. After working through conservative treatment options, many obstetricians now believe that pregnant women struggling to deal with morning sickness should be prescribed the FDA-approved anti-emetic Diclegis:

A Safe Alternative To Zofran

  • Doxylamine succinate and pyridoxine hydrochloride
  • the lone FDA-approved medication indicated for morning sickness
  • Pregnancy Category A

Zofran During Pregnancy: What The New Label Tells Us

Some families, however, say GlaxoSmithKline knows more about the potential risks of Zofran than the public does. In their birth defect lawsuits, hundreds of parents say that early animal studies actually found evidence that Zofran could hurt developing fetuses in rats and rabbits. This information was actively withheld from the public, parents allege, and may have been hidden from the FDA, as well.

Ondansetron, the active ingredient in Zofran, is now America’s most popular morning sickness drug. Millions of women have taken it during pregnancy. That means researchers have been able to investigate the drug’s potential risks for pregnancy in detail. Some teams have found worrying evidence that Zofran can increase the risk for birth defects – most notably, cleft palate and congenital heart defects.

Zofran’s new Pregnancy Risk information section acknowledges these findings, but remains hesitant, saying “available data do not reliably inform the association of Zofran and adverse fetal outcomes.” The label now summarizes the results of multiple studies, several of which have linked Zofran exposure to increased risks for congenital heart defects and cleft palate. This new labeling, however, was only published on September 28, 2016.

Did Birth Defect Study Information Come Too Late?

The problem for many parents remains in the past. While Zofran’s new labeling updates may prove beneficial for future patients, allowing better-informed conversations between pregnant women and their healthcare providers, it remains true that Zofran’s manufacturer only publicized these study results recently. Before September 2016, the drug’s pregnancy ranking remained the same – even after the birth defect findings were published.

The study linking Zofran to cleft palate, for example, was published in 2012, 3 years before the FDA phased out its letter-grade Pregnancy Category system. Parents argue that Zofran’s manufacturer had a duty to reclassify the drug, either to Pregnancy Category D or X:

  • Pregnancy Category D – There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks
  • Pregnancy Category X – Studies in animals or humans have demonstrated fetal abnormalities and / or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits

As we’ve seen, this change, one that families claim was a legal obligation, never came.

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