A new study has found evidence that children born to epileptic women taking Topamax might be at a higher risk of developing birth defect. Though the study, published this month in the journal “Neurology”, looked only at epilepsy patients taking Topamax, the findings may have serious implications for the millions of women of childbearing age who take the drug for migraine prevention.
Topamax, made by Ortho-McNeil Neurologics, a division of Johnson & Johnson, was originally approved to treat epilepsy in adults and children. In 2004, the approved uses of Topamax were expanded to include the prevention of migraine headaches. Generic versions of Topamax were approved by the Food & Drug Administration (FDA) in 2006. Topamax is also used off-label to treat bipolar disorder.
The study in “Neurology”, which was conducted by British researchers at the Royal Group of Hospitals in Belfast, Northern Ireland, involved 203 women who were taking Topamax either alone or in combination with another epilepsy drug when they became pregnant. Of 178 live births that occurred, three babies whose mothers took Topamax alone and 13 whose mothers took Topamax along with other anti-epilepsy drugs had major birth defects.
Four of the babies had cleft palates or cleft lips, which was 11 times higher than would be expected among women not taking epilepsy medication. Four male babies had genital birth defects, with two of these classified as major birth defects. Minor defects included a hole above the buttocks, a flattened head, toe webbing, clicky hips and immature hip joints. The birth weights weren’t significantly lower than in the normal population.
All epilepsy drugs are known to increase the risk of miscarriage and birth defects, and researchers conducting this study said the Topamax risk was similar to that seen with similar medications. However, more birth defects occurred in women taking Topamax along with the drug valproate, or valproic acid, than in women taking other epilepsy drugs or other Topamax drug combinations. Valproate is sold as Depakote by Abbott Laboratories and as Depakine by Sanofi- Aventis. Previous research has shown that valproate is associated with an increased risk of birth defects such as heart defects and spina bifida.
Women with epilepsy often have no choice but to continue taking drugs like Topamax during pregnancy because epileptic seizures also put fetuses at risk. Doctors treating such women must weigh the birth defect risks of these drugs against the risk posed by frequent seizures. However, unlike many other epilepsy drugs, Topamax is taken by millions of women of child bearing age for migraines, which means much more of the population could be at risk for birth defects associated with the drug.
In the years since receiving FDA approval for the treatment of migraines, Topamax has become one of the most widely prescribed drugs for the condition, which affects almost 30 million Americans. Women are three times more likely to suffer from migraines than men; women in their childbearing years are particularly vulnerable