Animal studies have revealed evidence of teratogenicity. After oral administration (up to 300 mg/kg/day) to mice throughout organogenesis, increased incidences of fetal malformations were observed at all doses (without maternal toxicity); maternal plasma drug exposures (AUC) at the low-effect dose (50 mg/kg/day) for embryofetal developmental toxicity were about 10-fold lower than that in humans at the maximum recommended human dose (MRHD). After oral administration (up to 40 mg/kg/day) to rats throughout gestation and lactation, adverse effects on offspring growth were observed during the postnatal period at the high dose, and neurobehavioral impairment was seen in offspring at the 2 highest doses; the no-effect dose (10 mg/kg/day) for prenatal and postnatal developmental toxicity was associated with maternal drug exposures less than that in humans at the MRHD. Oral administration (up to 90 mg/kg/day) to rats on postnatal day (PND) 7 resulted in widespread apoptotic neurodegeneration in the brain at all doses (a no-effect dose was not identified); brain development on PND 7 in rats corresponds to that beginning in humans during the third trimester of pregnancy and continuing for the first several months to years after birth. There are no controlled data in human pregnancy.

To monitor the outcomes of pregnant women exposed to antiepileptic drugs, a pregnancy registry has been established. Women taking this drug during pregnancy should be encouraged to enroll in the North American Antiepileptic Drug Pregnancy Registry by calling 1-888-233-2334 or visiting aedpregnancyregistry.org.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

The manufacturer makes no recommendation regarding use during pregnancy.

US FDA pregnancy category: Not assigned.

Risk summary: Based on animal data, this drug may cause fetal harm; no data available on use of this drug in pregnant women to inform a drug-related risk.

See references

Benefit should outweigh risk.

Excreted into human milk: Yes

Comments:
-No information is available on the clinical use of this drug during breastfeeding; however, amounts in breast milk appear low and would not be expected to cause any side effects in nursing infants.
-Developmental and health benefits of breastfeeding should be considered as well as the mother's clinical need for this drug.
-The effects in the nursing infant are unknown; potential side effects in the breastfed child due to this drug or the mother's underlying condition should be considered.

In a study, 5 healthy adult lactating women were treated with a 300 mg oral dose; drug exposures in breast milk were about 4 times those in maternal plasma. The calculated maximum relative infant dose was about 0.157 mg/kg/day based on average milk intake of 150 mL/kg/day, which is less than 1% of the maternal dose, and about 0.24% the labeled pediatric dose of 63 mg/kg/day.

See references