Category C—Associated with a 2-3X ↑'d risk of malformations, largely d/t an ↑'d risk for cleft lip with or without cleft palate and significant effects on cognitive functions and other matters. Effect on folic acid levels or metabolism is unknown ∴ the safest course is to start folic acid supplementation (4-5 mg/day) before conception, as is done with other antiepileptic agents. Avoid, if possible, during 1st trimester but, if required, monotherapy with the lowest effective dose is preferred. The risk for neonatal hypocalcemic seizures following in utero exposure requires further study.
Limited data on 5 breastfeeding infants exposed to topiramate showed infant plasma topiramate levels equal to 10-20% of the maternal plasma level. The effects of this exposure on infants are unknown. Caution should be exercised when administered to a nursing woman.
Dosage adjustment may be necessary for elderly with impaired renal function/
↓ dose by 50% in renally impaired patients (CrCl < than 70 mL/min/1.73 m2.
In hepatically impaired patients, topiramate plasma concentrations may be increased.