Sixty-eight infants (49.3%) had AED concentrations that were less than the lower limit of quantification. AED concentration was not greater than the lower limit of quantification for any infants breastfed by mothers taking carbamazepine, oxcarbazepine, valproic acid, or topiramate. Most levetiracetam (71.4%) and zonisamide (60.0%) concentrations in infants were less than the lower limit of quantification. Most lamotrigine concentrations in infants (88.6%) were greater than the lower limit of quantification.
The median percentage of infant-to-mother concentration was 28.9% for lamotrigine, 5.3% for levetiracetam, 44.2% for zonisamide, 5.7% for carbamazepine, 5.4% for carbamazepine epoxide, 0.3% for oxcarbazepine, 17.2% for topiramate, and 21.4% for valproic acid. Multiple linear regression models indicated that maternal concentration was significantly associated with lamotrigine concentration in infants, but not levetiracetam concentration in infants.
“Prior studies at delivery demonstrated that umbilical-cord concentrations were nearly equal to maternal concentrations, suggesting extensive placental passage to the fetus,” wrote Dr. Birnbaum and colleagues. “Therefore, the amount of AED exposure via breast milk is likely substantially lower than fetal exposure during pregnancy and appears unlikely to confer any additional risks beyond those that might be associated with exposure in pregnancy, especially given prior studies showing no adverse neurodevelopmental effects of breastfeeding while taking AEDs.”
The investigators acknowledged several limitations of their research, including the observational design of the MONEAD study. The amount of AED in participants’ breast milk is unknown, and the investigators could not calculate relative infant dosages. Only one blood sample was taken per infant, thus the results may not reflect infants’ total exposure over time.
The National Institute of Neurological Disorders and Stroke and the National Institute of Child Health and Development funded the research. The authors reported receiving research support from various pharmaceutical companies.
SOURCE: Birnbaum AK et al. JAMA Neurol. 2019 Dec 30. doi: 10.1001/jamaneurol.2019.4443.