Lacosamide use during breastfeeding: A case report and a literature review

Lacosamide, a voltage-gated sodium channel inhibitor, is an anti-seizure medication (ASM) from the age of 4. We report on the case of a woman treated with lacosamide for pharmacoresistant epilepsy who breastfed her infant for more than 6 months after birth. The infant's blood concentrations of lacosamide were 2.4 mg/L on Day 1 and less than 1 mg/L on Day 10 (reference values are 1-10 mg/L). No adverse drug reactions (ADRs) were reported for the infant. Eight cases of breastfeeding by mothers receiving lacosamide are described in the literature. These data confirm that a significant amount of lacosamide seems to pass into breast milk, with a relative infant dose (RID) above 20% in two cases but a low RID (1.8%) in another case. Nevertheless, blood tests, performed in two breastfed infants, revealed low concentrations of lacosamide. No ADRs were reported in eight of the breastfed infants; however, one infant, whose mother was also treated with levetiracetam, presented poor feeding and sleepiness at Day 15 of life. Given the well-known benefits of breastfeeding for both mothers and their infants, as well as the above reassuring data, breastfeeding of healthy full-term infants could be possible for mothers on lacosamide monotherapy. Nonetheless, relatives should be warned that data concerning the safety of lacosamide during breastfeeding are scarce and that long-term neurodevelopment outcomes in breastfed children are unknown. Clinical monitoring of breastfed infants for drowsiness, adequate weight gain, or cutaneous rash is recommended. Additionally, the infants' serum levels should be measured in case of an unexplained adverse reaction.