Has Lacosamide Been Studied for Safety in Pregnancy?
Lacosamide, marketed as Vimpat for partial-onset seizures, has been evaluated in pregnancy registries and observational studies, but data remain limited. The FDA classifies it as Pregnancy Category C, meaning animal studies show adverse effects, yet no adequate human studies confirm or rule out risks, and benefits may warrant use.[1]
What Pregnancy Registries Show
The U.S. Epilepsy Birth Defects and Neurodevelopment Outcomes Registry and the European Registry of Antiepileptic Drugs and Pregnancy (EURAP) tracked over 400 lacosamide-exposed pregnancies by 2023. No significant increase in major congenital malformations (rates around 2-3%, similar to unexposed epilepsy pregnancies) emerged, but sample sizes are small for detecting rare defects. Preterm birth and low birth weight risks appeared slightly elevated, possibly linked to epilepsy itself.[2][3]
Animal Study Findings
Reproductive toxicity studies in rats and rabbits at doses 2-4 times human levels caused embryofetal toxicity, including reduced fetal weight and skeletal variations. No teratogenic effects occurred at lower exposures. These findings prompted the Category C label, highlighting potential fetal harm.[1][4]
What Clinicians Advise for Pregnant Patients
Experts recommend monotherapy if possible, with lowest effective dose, and folate supplementation (4-5 mg daily). Lamotrigine or levetiracetam are often preferred due to stronger safety data. Breastfeeding data is reassuring, with low infant exposure (about 15% of maternal dose).[5]
Ongoing Research and Data Gaps
Post-marketing surveillance continues via the North American AED Pregnancy Registry. Long-term neurodevelopmental outcomes remain uncertain due to short follow-up periods. Patients should enroll in registries for better data collection.[2]
[1]: FDA Label for Vimpat (lacosamide), https://www.accessdata.fda.gov/drugsatfdadocs/label/2023/022253s059lbl.pdf
[2]: Hernández-Díaz et al., "Lacosamide in Pregnancy," Neurology (2022), https://n.neurology.org/content/99/5/e441
[3]: EURAP Study Group, "Antiepileptic Drugs in Pregnancy," Epilepsia (2021)
[4]: EMA Assessment Report for Vimpat, https://www.ema.europa.eu/en/documents/product-information/vimpat-epar-product-informationen.pdf
[5]: AAP Committee on Drugs, "Use of Antiepileptic Medications in Breastfeeding," Pediatrics (2021)