Monitoring of a common epilepsy drug during pregnancy reduces seizure risk

Nov 29 2007

Research at Emory University shows that monitoring the level of an epilepsy drug, called lamotrigine, in the blood helps reduce increased seizure activity and improve the overall health of pregnant women and their fetuses.

The findings are published Nov. 28 in the online edition of Neurology, the medical journal of the American Academy of Neurology.

The 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, according to some prior research studies.

“This is important data considering current treatment guidelines do not address how to dose epilepsy drugs once women become pregnant,” says study author Page Pennell, MD, associate professor of neurology, Emory University School of Medicine, and director of the Emory Epilepsy Program.

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

Dr. Pennell and her colleagues 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,” says Dr. Pennell. “Our findings provide a foundation for treatment guidelines to prevent increased seizure frequency and ultimately improve the health of the mother and fetus.”

Dr. Pennell says this type of drug monitoring is relatively easy since pregnant women can give blood for lamotrigine testing during their regular visits to an obstetrician or neurologist.

“It's really a benefit for both mothers and babies,” she adds.

The study, supported by grants from the National Institutes of Health, also found the amount of lamotrigine leaving the blood during pregnancy was higher in white women compared to black women.