Australian Study Links Fetal Malformation to Topamax

Melbourne, AustraliaA new study conducted by researchers in Australia suggests that Topamax side effects could include a risk of Topamax birth defects. The study, which included both valproate and topiramate side effects, examined the link between the use of antiepileptic drugs while pregnant and the incidence of birth defects.

For the study, published in the journal Acta Neurologica Scandinavica (3/6/13), researchers at the Royal Melbourne Hospital and University of Melbourne examined the data of 1,733 fetuses from 1,703 pregnancies. Of those fetuses, 147 were not exposed to any antiepileptic drug during pregnancy. The goal of the study was to determine whether there was a link between fetal malformations and use of antiepileptic drugs during pregnancy. Included in the study were valproate (Depakote), carbamazepine (Tegretol) and topiramate (Topamax).

Researchers found a statistically significant link between the use of topiramate while pregnant and the risk of having a baby born with hypospadias and brain maldevelopments. Hypospadias is a condition in which the opening of the urethra is located on the underside of the infant’s penis. The study’s authors recommended that more research was needed, specifically related to topiramate because it is being used more and more frequently to prevent migraines in women.

Topiramate is prescribed to treat certain types of seizures and to prevent migraine headaches. Studies have linked topiramate and other antiseizure medications to birth defects when infants were exposed to the medications prior to birth. Not all antiseizure medications are associated with the same birth defects.

Research from the North American Antiepileptic Drug (AED) Pregnancy Registry suggested infants exposed to topiramate prior to birth had a 1.4 percent prevalence of oral clefts, compared with infants exposed to other antiepileptic drugs who had a 0.38 to 0.55 percent prevalence. Infants who were not exposed to any antiepileptic medication had a 0.07 percent prevalence of oral cleft.

Based on that information, in 2011, the US Food and Drug Administration (FDA) issued a warning about the possible link between topiramate and oral cleft (including cleft lip and/or cleft palate). When it made its announcement, the FDA noted that the benefits and risks of the drug should be carefully weighed, especially when the drug is prescribed for non-life-threatening conditions. At the time, the FDA reclassified topiramate from Pregnancy Category C to Pregnancy Category D, meaning there is evidence of fetal risk based on human data.