Study Fails to Clarify Topamax Birth Defect Risk

A new study has proven inconclusive on <"">Topamax birth defects because of the small amount of Topamax patients involved in the fairly large study. The research, said WebMD, reviewed newer antiseizure medications taken by pregnant women during their first trimester.

The large study, which will appear in the Journal of the American Medical Association, essentially reviewed the antiseizure medication Lamictal (generic: lamotrigine), said WebMD. The study did reveal that a slightly increased risk in birth defects in expectant mothers versus other women who did not take antiseizure medications; however, only just a little over 100 women in the group of 800,000 women took Topamax (generic: topiramate), noted WebMD. The participants were part of the Danish registry study.

Researcher Anders Hviid, MSc, of Copenhagen’s Statens Serum Institut told WebMD that, “We cannot conclude anything or make any recommendations on [Topamax], based on this study,” he said. Use of antiseizure drugs in pregnant women is on the rise because while about one in 200 women take the medication for epilepsy, the medications are being used to treat other conditions, including migraines and bipolar disorder, noted WebMD.

The study reviewed data on 837,795 live births occurring in Denmark from January 1996 through September 2008, including 1,532 women who took a so-called second-generation antiseizure medication in their first trimester. Over 1,000 took Lamictal; 400, Trileptal (generic: oxcarbazepine), 100, Topamax, and about 60 each, Neurontin (generic: gabapentin) or Keppra (generic: levetiracetam), said WebMD. Some of the participants did take more than one medication.

The study revealed major birth defects in 3.2 percent of infants exposed to one of the drugs in the fetus’ early development; 2.4 percent of babies were not exposed to antiseizure drugs, said WebMD. About 4.6 percent who took Topamax and 3.7-4 percent who took Lamictal gave birth to infants with major birth defects, said WebMD.

Earlier this year, the U.S. Food & Drug Administration (FDA) moved Topamax from Pregnancy Category C to Pregnancy Category D, after data indicated that women taking the drug in the early months of pregnancy face a higher risk of having a baby with an oral cleft. The Pregnancy Category D designation means that there is positive evidence of human fetal risk based on human data, but potential benefits in pregnant women may outweigh risks in certain situations.

According to the FDA, 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 pregnancy experienced a 1.4 percent prevalence of oral clefts, compared with a prevalence of 0.38–0.55 percent in infants exposed to other antiepileptic drugs. Infants of mothers who did not have epilepsy and were not being treated with other antiepileptic drugs had a prevalence of 0.07 percent.

Oral clefts are birth defects that occur when parts of the lip or palate do not completely fuse together early in the first trimester of pregnancy, a time when many women do not know they are pregnant. They can range from a small notch in the lip to a groove that runs into the roof of the mouth and nose, possibly leading to problems with eating, talking, and to ear infections.

Topamax may also be linked to other birth defects. According to the FDA’s Adverse Event Report database, there have been a total of 244 reports made to the agency of injuries to children believed to be associated with the use of Topamax. Of those, more than 100 involved 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).

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