Drug monitoring reduces seizures in pregnant women with epilepsy

A popular epilepsy drug taken by pregnant women with epilepsy because of its mild risk of birth defects has been linked to increased seizure activity in up to 75 percent of pregnancies.

Now, new research shows that monitoring the level of the drug in the blood helps to reduce the increased seizure activity associated with the drug lamotrigine and improve the overall health of pregnant women and their fetuses. The findings are published November 28, 2007, in the online edition of Neurology®, the medical journal of the American Academy of Neurology.

“This is important data considering current treatment guidelines do not address how to dose epilepsy drugs once women become pregnant,” said study author Page B. Pennell, MD, with Emory University School of Medicine in Atlanta, GA, and member of the American Academy of Neurology.

For the study, 53 women taking lamotrigine underwent therapeutic drug monitoring every one to three months throughout their pregnancies.

Researchers measured seizure activity and the amount of lamotrigine in the blood since past studies have shown lamotrigine levels significantly drop during pregnancy, causing seizures to worsen. In the current study, the clearance of lamotrigine increased by 89 percent in the third trimester compared to non-pregnant levels. Dosages were adjusted depending on the lamotrigine blood levels with the goal of maintaining each patient's target concentration determined by pre-pregnancy information.

The study found that although 39 percent of women reported an increase in seizure activity during their pregnancy, 33 percent actually reported a decrease in seizures and 28 percent no change. The health of the babies born was similar to that found in women who do not have epilepsy.

“These rates are more consistent with what's been reported for pregnant women with epilepsy using other medications, and show the effectiveness of drug monitoring,” said Pennell. “Our findings provide a foundation for treatment guidelines to prevent increased seizure frequency and ultimately improve the health of the mother and fetus.”

“This type of drug monitoring is relatively easy since pregnant women can give blood for lamotrigine testing during their regular visits with their obstetrician or neurologist,” said Pennell. “It's really a benefit for both mothers and babies.”

The study also found the amount of lamotrigine leaving the blood during pregnancy was higher in white women compared to African American women.