MONDAY, July 21, 2008 (HealthDay News) -- Pregnant women who use the epilepsy drug topiramate alone or in combination with other epilepsy drugs may be increasing their risk of birth defects, British researchers report.
Topiramate (brand name Topamax) is a common anti-seizure medication used by many with epilepsy. It's also used to treat migraine headaches. Many similar drugs also increase the risk of birth defects, but until this report, the link between birth defects and topiramate had not been well studied.
"More research needs to be done to confirm these results, especially since it was a small study," lead researcher John Craig, of the Royal Group of Hospitals in Belfast, Northern Ireland, said in a news release from the American Academy of Neurology. "But these results should also get the attention of women with migraine and their doctors, since topiramate is also used for preventing migraine, which is an even more common condition that also occurs frequently in women of childbearing age."
The report is published in the July 22 issue of the journal Neurology.
For the study, the researchers collected data on women who became pregnant while taking topiramate alone or in combination with other epilepsy drugs.
Craig's team found that of the 178 babies born, 16 (4.8 percent) suffered from major birth defects. Among the babies with birth defects, three of the mothers were taking topiramate exclusively, while 13 were taking topiramate plus other epilepsy drugs.
Four of the babies had cleft palettes or cleft lips. That's a rate 11 times higher than one would expect among women not taking the drug, the researchers said.
Among male babies, four had genital defects, with two classified as "major defects." That's a rate 14 times higher than normal, the researchers reported.
The incidence of birth defects among women taking topiramate was higher than the rate of birth defects in the general population, which is about 1 percent to 2.5 percent. And there were more birth defects among women taking topiramate along with the epilepsy drug valproate, compared with women taking topiramate and another epilepsy drug.
Despite the risk, it's important that women maintain effective epilepsy control during pregnancy, because seizures can also harm the fetus. The risk of birth defects may be different among women taking topiramate to treat migraines, but these women should be monitored as well, the researchers said.
Dr. Orrin Devinsky, a professor of neurology, neurosurgery and psychiatry, and director of the New York University Epilepsy Center, said this study underscores the need for all women of childbearing years who take antiepileptic drugs to discuss preconception planning with their physician.
"All women should clearly understand the risks and benefits of their therapy," Devinsky said. "Until more information is available, topiramate use in women who plan on conceiving should be restricted to those in whom the drug is definitely needed for seizure control or other indications. Also, the mother should be informed of the potential risks to her child."
Another epilepsy expert, Dr. Edward Barry Bromfield, chief of the Division of Epilepsy at Brigham and Women's Hospital in Boston, agreed that women should be warned about the potential side effects of the drug.
"Women with epilepsy, if they depend on this drug to control their convulsive seizures, they should definitely continue it," Bromfield said. "If they are taking it for migraine prevention, chances are they would want to discontinue it before conception," he said.
For more on epilepsy, visit the U.S. National Library of Medicine.