Pregnancy Reduces Effectiveness of Popular Bipolar Drug

When women with bipolar disorder become pregnant, physiological changes reduce the effectiveness of one of the most commonly used drugs designed to treat the condition, a new study found.

According to the researchers from Northwestern Medicine, when women with bipolar disorder become pregnant, she and her doctor rarely identify the need to alter her medication in order to prevent symptoms from recurring. This is further compounded by a lack of research regarding dose changes for psychiatric medication during pregnancy.

In the new study, the scientists found the blood concentration of the popular drug lamotrigine decreases in pregnant women as their metabolism rises. This shift triggered a worsening of depressive symptoms in about half of the study's participants.

"Now physicians change the dose of the drug in response to women's symptoms worsening," said lead investigator Dr. Crystal Clark, an assistant professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine and a psychiatrist at Northwestern Memorial Hospital. "We need to optimize their medication dosing so they stay well."

The finding is not only important for the health of the mother, but of the child as well, the researchers note.

"The safety of the fetus is at risk," Clark said. "Pregnant women that are depressed are less likely to take care of themselves which often leads to poor nutrition, lack of compliance with prenatal care and isolation from family and friends. It has also been linked to premature births and babies with low birth weights among other poor birth outcomes."

The study's results will help physicians both understand how to increase doses during pregnancy as well as reduce them postpartum in order to avoid toxicity, Clark noted.

The study was published in the journal American Journal of Psychiatry.