A new research study shows how the physiological changes that accompany pregnancy can diminish the effects of lamotrigine (Lamictal), a drug often used to treat bipolar disorder.
Northwestern Medicine researchers say the interaction can make a woman more vulnerable to recurring episodes of bipolar disorder.
When a woman with bipolar disorder becomes pregnant, she and her physician often don’t realize her medication needs adjusting to prevent symptoms from coming back — a higher risk during pregnancy.
There also is little information and research to guide dosing for psychiatric medications during pregnancy.
The new study shows the blood concentration of lamotrigine decreases in pregnant women.
About half of the women in the study had worsening depressive symptoms as their lamotrigine blood levels dropped. The drug levels fall because women have increased metabolism during pregnancy.
“Now physicians change the dose of the drug in response to women’s symptoms worsening,” said lead investigator Crystal Clark, M.D. “We need to optimize their medication dosing so they stay well.”
The study results will help physicians understand how to increase their patients’ doses during pregnancy and then reduce them postpartum to avoid toxicity, Clark said. Guidelines for prescribing the drug for pregnant women with the disorder also are included.
The study is found in the American Journal of Psychiatry. Experts say approximately 4.4 million women in the U.S. have bipolar disorder with women of childbearing age having the highest prevalence.
Depressive episodes — as opposed to manic — are most likely to recur in pregnant women with bipolar disorder.
“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.”
Source: Northwestern University