Abstracts

Rationale: Pharamacokinetic characteristics of anti-epileptic medications determine therapeutic approach in regards to both efficacy and safety profile. The novel anti-epileptic drug lacosamide (LCM) was recently approved for adjuvant treatment of partial onset seizures in adults. Thus far, pharmacokinetic studies of LCM show that it is renally excreted, minimally bound to plasma proteins and has no known clinically relevant drug-to-drug interactions. It is still unclear if pharmacokinetic characteristics of LCM can differ based on race, and more specifically in the African American population. Methods: Retrospective evaluation of patients seen in the epilepsy clinic from December of 2010 through May of 2011 revealed 19 patients [10 Caucasians (6 females and 4 males) and 9 African Americans (3 females and 6 males)] treated with LCM as an adjunctive therapy in patients with intractable partial epilepsy. The age range was 21 to 50 years (mean 34.2) in the African American (AA) group and 18 to 49 years (mean of 34.3) in the Caucasian (C) group. Total LCM serum concentrations were obtained once per patient. In one AA patient, levels were drawn twice due to dose adjustments. A total of 10 serum levels were analyzed per group and ANOVA s t-tests were used to look for statistical significance. Figure 1 plots LCM serum level with respect to LCM dose (mg/kg). Results: The mean LCM level was 5.32 mg/kg for African Americans, and 6.09 mg/kg for Caucasians (F(1,18) = 0.67, p = 0.42). The average total daily dose was 390 mg for AA, and 260 mg for C (F(1,18) = 4.84, p = 0.04). Dose (mg/kg) was 5.172 for AA, and 3.195 for C (F(1,18) = 4.71, p = 0.04). Independent groups ANOVAs showed no effect for LCM level, but an effect for total daily dose, and dose expressed as mg/kg. In the patients taking a daily dose of 200 mg, the average LCM level was 4.07 g/mL (? = 0.15) for the AA group and 4.72 g/mL (? = 2.01) for the C group. On 400 mg per day, the average LCM level was 5.94 g/mL (? = 1.16) for the AA group and 9.00 g/mL (? = 0.99) for the C group. Conclusions: It appears that the African American group tends to achieve lower serum lacosamide levels compared to the Caucasian group at similar LCM dosing without reaching statistical significance. Indirectly, this is supported by the finding that the AA group received higher doses of lacosamide (p=0.04). More studies regarding the pharmokinetics of lacosamide are needed with further investigations in regards to racial differences.