Can physiologic menstrual cycle change serum lamotrigine concentration?

PURPOSE The present study aimed to compare the serum LTG levels during the early-/mid-follicular (low estradiol) and mid-luteal (high estradiol) phases of the physiologic menstrual cycle. METHOD In a cross-sectional study, 20 women with epilepsy were recruited. Participants had been on monotherapy with LTG for at least two months. All the subjects had normal menstrual cycles. Blood samples for each patient were taken whilst fasting during the early-/mid-follicular (Days 3-5) and mid-luteal phases (Days 20-24). All samples were analyzed in batched assays. A comparison of the serum LTG levels was carried out using the Mann-Whitney U test Data were analyzed with the SPSS program, version 16 (SPSS Inc., Chicago, IL), p-values below 0.05 were considered significant. RESULTS The mean serum LTG levels for the early-/mid-follicular and mid-luteal phases were 4.28±2.76 mg/ml (SD) and 3.86±2.06 mg/ml (SD), respectively. There was no statistically significant difference in serum LTG level between the (low estradiol) early-/mid-follicular and (high estradiol) mid-luteal phases in our patients (p-value=0.23). CONCLUSION The serum level of LTG does not alter significantly during the menstrual cycle.