Lamotrigine Use in Lactating Women: Passage Into Breast Milk and Infant Exposure

Lamotrigine, an antiseizure medication used for epilepsy and bipolar disorders, is often prescribed to women of childbearing age due to relatively low teratogenic risk. It is known that lamotrigine use in lactation leads to detectable concentrations in breast milk, although concentrations vary significantly among individuals.

A 35-year-old pregnant woman with epilepsy presented to our outpatient clinic. She was seizure-free and was taking lamotrigine 200 mg once daily. She is highly motivated to breastfeed her baby after birth but is concerned about the infant's exposure to lamotrigine through lactation. Lamotrigine concentrations were measured in both the breast milk and plasma of the suckling infants.

Although lamotrigine is excreted into breast milk, and detectable in infants, the benefits of breastfeeding should not be overlooked. Higher plasma concentrations generally lead to higher breast milk concentrations, so aiming for the lowest possible maternal plasma levels is beneficial. These findings underscore the importance of TDM in this population.