The Food and Drug Administration said Monday that the drugs, including Depakote and Depacon, should never be taken by pregnant women for the prevention of migraine headaches.
The pills, which all contain the ingredient valproate sodium, already carry a boxed warning about the risk of birth defects. But the FDA said it is adding new warnings to the drugs after a study showed they decreased IQ scores in children whose mothers took them while pregnant.
"We have even more data now that show the risks to the children outweigh any treatment benefits for this use," said Russell Katz, the FDA's director for neurology drugs.
Earlier this year, researchers at Emory University reported that valproate-containing drugs were connected with an 8 to 11 point reduction in IQ scores for children at age 6. The study compared children whose mothers had taken different classes of neurological drugs while pregnant. The results supported similar findings from when the children were age 3.
Depakote and similar drugs are also used to treat bipolar disorder and seizures. While the FDA said it would not contraindicate the drugs for those uses, the agency said women of child-bearing age should only them as a last resort.
"Women who can become pregnant should not use valproate unless it is essential to managing their medical condition," the agency said in a statement.
Depakote is marketed in the U.S. by AbbVie, which was spun off earlier this year from parent company Abbott Laboratories. AbbVie also markets several other versions of the drug, including Depacon, an injectable formulation. The FDA's warning also affects Stavzor, a pill marketed by Noven Pharmaceuticals for bipolar disorder.
The FDA said it is working with the drug manufacturers to change their products' pregnancy code for migraines to X. The code indicates that the drug's risks outweigh its benefits for the given use.