Study Finds Epilepsy Drug Birth Defect Risk Varies Among Medications, Dosages

A new study out of the United Kingdom has found differing birth defect risk between the four most popular epilepsy drugs – <"">valproic acid (Depakote), lamotrigine (Lamictal), carbamazepine (Tegretol), and phenobarbital. Though each of the medications do make it more likely that a pregnant woman will have a child with a birth defect, the authors of the study say their findings could help doctors devise strategies to cut those risks.

The study, published in Lancet Neurology, involved just over 3,900 woman and 4,540 pregnancies. Out of those, 230 children were born with a birth defect, including a heart defect or spina bifida. All of the epilepsy drugs involved in the study were associated with birth defects, and higher doses carried the greatest risk. However, the lowest doses of lamotrigine and carbamazepine were associated with the lowest risk.

“Our results show that dose selection is as crucial as the choice of drug,” the study authors wrote.

An editorial accompanying the study said findings were “important” because they offered alternatives to the drugs linked most strongly to problems. The author of that editorial added that: “The data provide another reason for use of the lowest dose of a drug associated with optimum seizure control.”

Its been known since the 1960s that epilepsy drugs were associated with birth defects, but recently, that association has been getting more attention. In 2009, the US Food & Drug Administration (FDA) warned that women of childbearing potential should only take Depakote and other valproic acid medications if it is essential to manage their medical condition. The warning was issued after data from the North American Antiepileptic Drug (NAAED) Pregnancy Registry indicated that the rate of major malformations in babies born to women with epilepsy taking such medications as monotherapy was almost 4 times higher than the rate of major malformations in babies born to women with epilepsy taking a different antiepileptic drug.

Earlier this year, the agency moved <"">Topamax (not included in the Lancet study) from Pregnancy Category C to Pregnancy Category D, after data from the NAAED 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.

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