Many women with epilepsy have breakthrough seizures when they get pregnant, and researchers say they've figured out why.
Their new study shows that pregnancy can trigger steep drops in blood levels of certain antiepileptic drugs soon after conception.
"When it comes to epilepsy, maintaining a fine-tuned medication regimen is critical. Some people mistakenly believe that changes in the drugs' blood concentration won't occur until after 20 weeks of pregnancy, but our study shows how important it is to start monitoring and adjusting patients' medication dosages early on," said lead study author Dr. Page Pennell, chair of neurology at the University of Pittsburgh.
"Nearly half of all pregnancies in the United States are unplanned, so it is important to ensure that doctors have a clear picture of each patient's baseline drug level even if they are not trying to conceive," Pennell said in a university news release.
For the study, Pennell and her colleagues analyzed blood concentrations of 10 commonly used antiseizure drugs in women with epilepsy at different stages of pregnancy and after childbirth.
There were dramatic declines in the levels of seven drugs, ranging from about 30% for lacosamide (Vimpat) to over 56% for lamotrigine (Lamictal), the investigators found.
The researchers also found that the declines in blood levels of the drugs occurred just days after conception.
"Identifying which antiseizure medications may have changes in concentrations and at what point in pregnancy those changes occur is important for determining which patients may need to be monitored more closely during pregnancy and after delivery," said study co-author Angela Birnbaum, a professor of experimental and clinical pharmacology at the University of Minnesota.
The findings highlight the need to increase doses of certain antiseizure drugs and closely monitor their levels in epilepsy patients when they're pregnant, the study authors concluded.
The findings were published online Feb. 14 in JAMA Neurology.
There's more on epilepsy and pregnancy at the American Academy of Family Physicians.
SOURCE: University of Pittsburgh, news release, Feb. 14, 2022