New Study Inconclusive on Topamax Birth Defect RiskMay 20, 2011 | Parker Waichman LLP
A study that offers reassurance to expectant mothers who take new epilepsy drugs unfortunately doesn’t provide much comfort to those taking Topamax. The study, which found that most newer-generation medications carried a lower risk of birth defects than older drugs like Depakote, was unable to draw any conclusions about Topamax.
Recently, a growing body of evidence has indicated that women who take Topamax in early pregnancy may face a higher risk of having a child with a birth defect. In March, the U.S. Food & Drug Administration (FDA) moved Topamax from Pregnancy Category C to Pregnancy Category D, a classification that means there is positive evidence of human fetal risk based on human data. The FDA made this decision after data from the North American Antiepileptic Drug (AED) Pregnancy Registry indicated that infants exposed to Topamax as a single therapy during the first trimester of were more likely to be born with an oral cleft - cleft lip or cleft palate.
A recent survey of the FDA's Adverse Event database revealed over 100 reports of possible Topamax birth defects, including 29 oral clefts, 29 limb malformations, 27 heart defects, 26 reports of other congenital defects, 23 cranio-facial defects, 15 reports of spina bifida/spinal malformations, and 5 reports of persistent pulmonary hypertension of the newborn (PPHN).
Unfortunately, this new study, published in the Journal of the American Medical Association, could not make any conclusions or recommendations about Topamax. The study drew data from more than 800,000 women included in a Danish registry, but despite being one of the largest studies ever to examine the issue, only 100 of the women in the registry treated with a new-generation epilepsy drug took Topamax.
Of the women in the registry who took newer epilepsy drugs, 1,000 took Lamictal. Another 400 took Trileptal, and 60 each took Neurontin and Keppra.
Of the infants exposed to one of the drugs in early pregnancy, 3.2% were born with a major birth defect, compared to 2.4% of babies who were not exposed to any of the drugs. Among the women who took Topamax, 4.6% gave birth to a child with a birth defect. From 3.7% to 4% of women who took Lamictal had babies with major birth defects.
While the study did not calculate birth defect risks for older drugs like Depakote, previous studies have long linked these drugs to a higher risk of birth defects. In 2006, the FDA added a “black box” warning about the potential risk of a birth defect from Depakote use during pregnancy. The warning came after a study found that 20% of pregnant mothers who took Depakote during pregnancy had a child with birth defects.