Breastfeeding by mothers on antiepileptic therapy generally safe
A prospective cohort study of mothers taking antiepileptic drugs (AEDs) and their breastfed infants has found substantially lower AED concentrations in infant vs maternal blood, with nearly half of all obtained AED concentrations in nursing infants being less than the lower limit of quantification (LLoQ).
“The American Academy of Pediatrics recommends breastfeeding as the sole nutrition for the first 6 months of life, given the multiple benefits to both the child and the mother. However, no consensus exists for the safety of breastfeeding when the mother is receiving AEDs,” wrote the researchers. [Pediatrics 2012;129(3):e827-e841; American Academy of Pediatrics. Breastfeeding, https://www.aap.org/en-us/advocacy-and-policy/aap-health-initiatives/Breastfeeding/Pages/Benefits-of-Breastfeeding.aspx] “The primary goal of this study was to measure blood concentrations of AEDs in mothers and the infants they breastfed to provide direct, objective information on the extent of AED exposure via breastfeeding.”
The study was conducted between December 2012 and October 2016 at 20 sites in the US. Of the 345 infants, 222 (64.3 percent) were breastfed after delivery. Blood samples were collected from 146 breastfed infants and their mothers at the same visit between 5 and 20 weeks after birth. Mothers with missing concentration data and the two outliers were excluded. Because of polytherapy, there was more than one AED concentration available for some infants, resulting in 164 matching infant-mother concentration pairs from 135 mothers and 138 infants (including 3 pairs of twins). [JAMA Neurol 2019, doi: 10.1001/jamaneurol.2019.4443]
“Sixty-eight of 138 infants [49.3 percent] had AED concentrations that were below the LLoQ. No infants who were breastfed by mothers taking carbamazepine, oxcarbazepine, valproic acid, or topiramate had drug concentrations above the LLoQ,” wrote the researchers. However, the LLoQ for valproic acid was 10 to 20 times higher than that of the other AEDs, which is reflective of the higher target concentration of valproic acid used in adults.
Most levetiracetam and zonisamide concentrations in infants were below the LLoQ (71.4 percent and 60.0 percent, respectively), although most lamotrigine concentrations (88.9 percent) in infants were above the LLoQ. “It should be noted that the LLoQ was lower for lamotrigine than for some of the other AED concentrations,” the researchers explained.
The median percentage of infant-to-mother AED concentration was 28.9 percent for lamotrigine, 5.3 percent for levetiracetam, 44.2 percent for zonisamide, 5.7 percent for carbamazepine, 5.4 percent for carbamazepine epoxide, 0.3 percent for oxcarbazepine, 17.2 percent for topiramate, and 21.4 percent for valproic acid.
“Overall, AED concentrations in infants who were breastfed were low compared with the AED concentrations in their mothers. Our findings may explain why prior studies have found no adverse neurodevelopment effects of breastfeeding while the mother is taking an AED,” commented the researchers. [N Engl J Med 2009;360:1597-1605; JAMA Pediatr 2014;168:729-736]
“On the basis of infant exposure via breastfeeding from maternal AEDs, the results of this study add support to the general safety of breastfeeding by mothers with epilepsy who take AEDs,” they concluded.