Teratogenicity of Topiramate is Not New But the Warnings Are

The FDA is finally requiring the well-known antiepileptic drug Topiramate to carry a label that warns of topamax cleft palate birth defects.

The FDA warning, which came out in March of 2011, indicated that new data from two pregnancy registries showed an elevated risk for cleft lip and cleft palate birth defects in babies born to mothers who took topiramate during pregnancy. In addition, the FDA cautioned that “The benefits and the risks of topiramate should be carefully weighed when prescribing this drug to women of childbearing age, particularly for conditions not usually associated with permanent injury or death.” Those risks are potentially great that the FDA cautions that “alternative medications that have a lower risk of oral clefts and other adverse birth outcomes should be considered for these patients.”

For many women and children, however, this warning came years too late. Despite the reference the FDA makes to “new data”, the fact is that there are studies from several years ago that show the pregnancy risks of topiramate.

For example, as early as 2008, a study conducted in the UK and published in the medical journal Neurology looked at the pregnancy outcomes of 203 women who took topiramate during their pregnancy. The study found that 9% of the children had major congenital malformations, with over 2% of the children born suffered from oral cleft defect. That rate amounts to 11 times the amount of oral clefts observed in the control group, leading the researchers to conclude that there are serious concerns about topiramate use during pregnancy.

This raises serious questions about what took the FDA so long to warn the public about these risks. Topiramate, sold under the brand name Topamax, is used for treating eplilepsy and migraine headaches. Between 2007 and 2010, approximately 32.3 million prescriptions for topiramate were dispensed to 4.3 million patients. Those numbers are significant, as it is likely that thousands of women could have benefitted if the FDA had simply acted sooner.