Ethosuximide in epileptic women during pregnancy and lactation period. Placental transfer, serum concentrations in nursed infants and clinical status.

A total of 10 epileptic mothers treated with ethosuximide (ES) as well as their 13 newborns were included in this study. At birth foetal/maternal serum concentration ratios were 0.97 +/- 0.02 (n = 7) and ES half-lives in three neonates were 32, 37 and 38 h. The breast milk concentrations of ES were similar to those in maternal serum (milk/serum: 0.86 +/- 0.08, n = 12) and the nursed infants maintained serum levels between 15 and 40 micrograms/ml. Two major malformations (bilateral clefting, hare-lip) were observed in two neonates whose mothers received either ES/PB or ES/PMD comedication. The number of minor anomalies was higher in the ES group (6.2, n = 12) than in the pair-matched control group of infants born to non-epileptic mothers (2.1, n = 10). Neonatal behaviour complications occurred in seven infants, two of them were severely affected.