Newer Epilepsy Drug Cuts Risk of Birth Defects
But long-standing drug increases the chances, study finds
FRIDAY, March 25, 2005 (HealthDay News) -- A newer epilepsy drug designed to control seizures appears to reduce the risk of birth defects for women with the disorder who become pregnant.
But a long-standing drug does increase the chances of birth defects, according to new research.
The findings appear in this week's issue of Neurology, the journal of the American Academy of Neurology.
Pregnancy for women with epilepsy can be difficult because the drugs they must take to control their seizures have been associated with a three-fold risk for birth defects.
The newer drug, lamotrigine, introduced in the last decade, appears to reduce the risk for birth defects to 2.9 percent, which is similar to the 2-to-3 percent risk for the general population, the study reported.
The finding is based on an ongoing 12-year registry that compiles information about the risk of birth defects among the children of some 400 women who took lamotrigine while pregnant. The registry is sponsored by GlaxoSmithKline, the manufacturers of lamotrigine, sold as Lamictal.
While the number of pregnancies reported in the registry is still too small to make absolute scientific conclusions, the findings consistently show that taking lamotrigine alone is associated with a lower risk of birth defects, according to the lead author of the study, Marianne Cunnington, the chief epidemiologist for GlaxoSmithKline.
"We have increasing confidence in the data and feel it is very important information that provides doctors with concrete data to base risk/benefit assessments," she said.
"You can say with some power that it [lamotrigine] looks pretty safe," agreed Dr. Patricia Penovich, of the Minnesota Epilepsy Group in St. Paul, who wrote an accompanying editorial in the journal. "It's very promising."
Conversely, this and other research in Neurology reported that valproic acid, a widely used older anti-seizure drug, was associated with a higher rate of birth defects as well as a higher incidence of neurophysiological problems among children whose mothers took the drug.
In the GlaxoSmithKline registry reports, the researchers found that if women took lamotrigine with valproic acid, their risk of having children with birth defects jumped to 12.5 percent.
Another study in the March 22 Neurology reported on 149 women who took valproic acid while pregnant. Among these women, there were 16 infants with birth defects -- a 10.7 percent birth defect rate. These women were three times more likely to have babies with birth defects than women who had taken other anti-seizure drugs. And they were seven times more likely to have a baby with a birth defect than women in the general population, the study found.
The findings were based on a review of the North American Antiepileptic Drug (AED) Pregnancy Registry.
And in a third study in the journal, researchers found that children exposed to valproic acid while in the womb were more likely to have lower verbal IQ scores than children whose mothers took other epilepsy medication or who took no drug while pregnant.
What's more, 22 percent of the children whose mothers had taken valproic acid while pregnant had IQ scores in the extremely low -- or mentally impaired -- range. In the general population, only 2 percent to 3 percent of children would be likely to fall into this category, said the researchers, from the University Department of Neurosciences in the Walton Centre of Neurology and Neurosurgery in Liverpool, England.
The scientists recruited 163 mothers with epilepsy and their 249 children. They found in a series of tests that the 41 children who were exposed to valproic acid in the womb were more likely to have lower verbal IQ scores.
But, doctors note, choosing anti-seizure medication is more than just a matter of picking the drug with the least risk for birth defects.
"The first aim is to be seizure-free," said Penovich, because seizures can harm both a woman and her unborn child.
Also, people have idiosyncratic responses to anti-seizure drugs -- different drugs or combinations of drugs work differently in different patients. So some people might have better responses to the older drugs than to the newer ones, said Dr. John Messenheimer, senior director for clinical research on epilepsy at GlaxoSmithKline.
While two-thirds of people with epilepsy can be treated with one drug, called monotherapy, the remainder of patients need a combination of drugs to remain healthy, Penovich said.
"The older drugs are still widely used world-wide, and valproic acid and other drugs have value in terms of efficacy," Messenheimer said.
The bottom line, these health professionals said, is that as more scientific data becomes available to doctors and their patients, the more informed they can be about their care.
"The way this information should be used is that caregivers and these women should be aware of this developing information and should become educated," said Penovich.
Then, women who are planning families, and even young girls newly diagnosed with epilepsy, can work with their doctors to come up with the most effective risk/benefit treatment plan with an eye toward future pregnancy, she said.
For more information on enrolling in a drug registry if you have epilepsy and are planning to have a baby, visit the Epilepsy Foundation.