LOS ANGELES—How often should women with epilepsy have their medications monitored during pregnancy? The answer seems to be monthly, according to research presented at the 54th Annual Meeting of the American Epilepsy Society. Plasma levels of antiepileptic drugs (AEDs) decline frequently and unpredictably throughout pregnancy and during the postpartum period, and persistent monitoring is needed for optimum seizure control, the researchers said.

"Approximately one quarter to one third of women with epilepsy will have an increase in seizures during pregnancy," said Sandra D. Clements, RN, NP, a Nurse Practitioner in the Department of Neurology, Emory University School of Medicine, in Atlanta. Most dangerous are generalized tonic-clonic seizures, which can result in maternal and fetal hypoxia and acidosis, as well as prolonged depression of the fetal heart rate. In rare instances, convulsive seizures have been reported to cause fetal intracranial hemorrhages and stillbirths.

CHECKUPS EACH TRIMESTER ARE NOT ENOUGH

"Our study shows the need to change the practice parameters for monitoring drug levels in pregnant women," Ms. Clements said. Currently, the Quality Standards Subcommittee of the American Academy of Neurology recommends monitoring AED levels at the beginning of each trimester and during the last month of pregnancy. Additional tests are only advised if patients have a seizure, experience side effects, or if they are noncompliant. Monthly drug level monitoring, the researchers countered, should be warranted for all women with epilepsy.

In this study, monthly total and free plasma AED levels were obtained from 18 consecutive pregnant women in the Emory Epilepsy Clinic. The occurrence of a seizure attack was tracked and documented, then compared to any changes in medication drug levels. The medications used by study participants were carbamazepine, phenytoin, valproate, and lamotrigine.

NO PARTICULAR PATTERN FOR DRUG TYPE OR TRIMESTER

As expected, seizures were slightly more likely to occur with decreases in AED levels, the researchers found. Eighteen intervals were marked by significant AED level declines with seizures occurring during five, they reported. Forty intervals showed steady AED levels with seizures occurring during eight.

Among the 10 patients who had at least five blood draws, seven women had significant AED level declines (greater than 20%) from one month to the next despite stable or increasing antiepileptic drug doses, the researchers reported.

Overall, there was no particular pattern for AED type or for which trimester the declines occurred in, they said. Carbamazepine was the least likely of the AEDs to show significant decline; however the changes that did occur were often substantial, particularly in the last two trimesters, the researchers reported. Lamotrigine, they noted, required preemptory dosage increases to prevent decreasing levels. The other medications used in the study were associated with declines throughout the entire pregnancy.

ALTERED METABOLISM DURING PREGNANCY MAY PROVOKE SEIZURES

According to the postpartum data of eight patients, plasma levels of AEDs increased 14% to 105% after the pregnancy. Five of the eight patients demonstrated increased plasma medication levels despite decreased dosages, the researchers pointed out. "The increase in postpartum levels with all AED levels corroborates the altered metabolism that occurs during pregnancy," they suggested.

"More frequent level monitoring should become standard by neurologists and obstetricians caring for their pregnant patients with epilepsy," the researchers concluded.

NR

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