Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. Antiepileptic drug exposure in infants of breastfeeding mothers being treated for epilepsy is low.

Evidence Rating Level: 2 (Good)

While breastfeeding for the first 6 months of life is currently recommended by the American Academy of Pediatrics, no consensus exists for the safety of breastfeeding when the mother is receiving antiepileptic drugs (AEDs). Previous studies have reported no adverse neurodevelopmental effects in infants breastfed by mothers taking AEDs, but no studies have measured blood concentrations of AEDs in mothers and infants to provide objective information on the extent of AED exposure via breastfeeding. In this prospective cohort study, 351 women and their 345 infants were studied to examine the percentage of infant-to-mother concentrations of AEDs using blood samples collected from infants who were breastfed and their mothers at the same visit between 5 and 20 weeks after birth. Of the 345 infants, 64.3% were breastfed after delivery, and 42.3% had AED concentrations available from a visit 5 to 20 weeks after births. Ultimately, 164 matching infant-mother concentrations were available for analysis from 135 mothers and 138 infants. The infant cohort had a median age of 13 weeks (range 5 to 20 weeks), and mothers had a median age of 32 years (range 18 to 47), and 87.4% of mothers were white. Most mothers (82.2%) were receiving monotherapy, and there was no difference in blood concentrations in infants who were breastfed from mothers receiving monotherapy versus polytherapy. Approximately half of the infants (49.3%) had AED concentrations less than the lower limits of quantification (LLoQ), and only infants exposed to lamotrigine, levetiracetam and zonisamide had AED concentrations over the LLoQ. The median percentage of infant-to-mother concentration for all 7 antiepileptic drugs and 1 metabolite (carbamazepine, carbamazepine-10,11-epoxide, levetiracetam, lamotrigine, oxcarbazepine, topiramate, valproate, and zonisamide) ranged from 0.3% (range 0.2% to 0.9%) to 44.2% (range, 35.2% to 125.3%). Using multiple linear regression models using data from 52 infant-mother pairs in which the mothers were taking lamotrigine, and 16 in which the mothers were taking levetiracetam, researchers found that only maternal lamotrigine concentrations were significantly associated with plasma lamotrigine concentrations in infants (Pearson correlation coefficient 0.58, p<0.001). Overall, this study indicates that AED drug exposure in infants being breastfed by mothers taking AED therapy is low. The infants in the study will be followed up until the age of 6 years to determine long-term outcomes.

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