Abstracts

Rationale: The use of lamotrigine (LTG) in women of childbearing age is preferred by many physicians because of published data regarding fetal safety. However, LTG clearance increases during pregnancy with a consequent fall in plasma levels and the risk of seizure aggravation. Our aim was to assess seizure occurrence during pregnancy in women with epilepsy and LTG monotherapy. Methods: Clinical and Laboratory data were retrospectively reviewed in pregnant women with epilepsy and LTG monotherapy, who were followed at a tertiary epilepsy center. At least one value of LTG serum level was present for seven patients in the first trimester and in all women in the following trimesters. LTG ratio was calculated by multiplying LTG serum level (mg/L) by 100, and dividing the result by the prescribed LTG dose (mg). Results: There were 11 patients, age 27±5 (19-37 years). Epilepsy duration was 8.6±6.9 years. Five patients had localization-related epilepsy (LRE) and six- generalized epilepsy. At least 3 month seizure freedom was documented in nine patients prior to pregnancy. Despite LTG serum level guided dose adjustments, seizures occurred only in patients with LRE (p=0.002). LTG ratio decline, as compared to pre-pregnancy values, was most prominent in the first trimester (p=0.011), similar in both patients with and without seizures. A significant post-pregnancy LTG ratio increase was observed in all the patients (p<0.0001). Age, epilepsy duration, three month seizure freedom and LTG levels prior to pregnancy did not affect seizure occurrence.Conclusions: Seizure occurrence during pregnancy in patients with epilepsy and LTG monotherapy is significantly affected by the type of epilepsy syndrome.