Is Ethosuximide safe while breastfeeding?

Effects on the breastfed infant

An infant whose mother was taking ethosuximide 250 mg daily began exclusive breastfeeding on day 2 postpartum and continued through 4.5 months of observation. The infant developed normally during this time and had no signs of an adverse reaction.[ 3 ] Sedation, poor sucking and poor weight gain during the first 4 weeks of life occurred in a breastfed newborn whose mother was taking ethosuximide.[ 4 ] The reaction was possibly caused by ethosuximide in breastmilk; however, the mother was also taking primidone and valproic acid. Three fully breastfed infants and a mostly formula-fed whose mothers were taking ethosuximide had no adverse reactions observed during the first 1.5 to 4.5 months of life.[ 5 ]

Effects on milk supply

Relevant published information was not found as of the revision date.

Levels in milk

In published reports of anticonvulsant use during breastfeeding, most women were taking a combination of anticonvulsants. Some other anticonvulsants (e.g., phenytoin, carbamazepine) stimulate the metabolism of other drugs including anticonvulsants, whereas others (e.g., valproic acid) inhibit the metabolism of other drugs. Therefore, the relationship of the maternal dosage to the concentration in breastmilk can be quite variable, making calculation of the weight-adjusted percentage of maternal dosage less meaningful than for other drugs in this database. Maternal Levels. A woman with epilepsy was taking primidone 250 mg and ethosuximide 500 mg orally every 12 hours. She did not nurse her infant, but her milk flow was maintained to collect milk for study. Breastmilk ethosuximide levels were 55 to 70 mg/L on 4 occasions (times with respect to doses not stated) on days 3 to 5 postpartum.[ 1 ] Four ethosuximide breastmilk levels were measured between days 3 and 32 postpartum at unstated times after the dose in an unstated number of women who were taking ethosuximide and other anticonvulsants in unstated dosages. Ethosuximide milk levels averaged 21.3 mg/L (range 18 to 24 mg/L), while maternal serum levels averaged 29.3 mg/L.[ 2 ] A woman with epilepsy was taking oral ethosuximide 250 mg daily as a single agent during pregnancy and breastfeeding. Breastmilk samples were measured on several occasions during the first 4 months postpartum. Maternal serum and milk levels increased to higher levels between 1 and 2 months postpartum and then decreased, although the times of collection with respect to the doses were not reported. Milk levels on day 3 postpartum were about 31 mg/L, increased to about 55 mg/L at 1 month postpartum and decreased to about 42 mg/L at 4.5 months postpartum.[ 3 ] Breastmilk ethosuximide levels were measured 1 to 4 times in 5 mothers who were taking ethosuximide alone (1 woman) or with other anticonvulsants (4 women). Ethosuximide milk levels averaged

Alternatives LactMed lists

• Divalproex
• Gabapentin
• Lamotrigine
• Oxcarbazepine
• Phenytoin
• Valproic Acid