Influence of Dose and Antiepileptic Comedication on Lacosamide Serum Concentrations in Patients With Epilepsy of Different Ages

Background: Lacosamide (LCM) is a new antiepileptic drug (AED). The purpose of the study was to investigate the effects of LCM dose, body weight, height, sex, age, and concomitant AEDs on LCM trough serum concentrations (at a steady state) in patients with epilepsy. Methods: A total number of 3154 blood samples of 973 consecutive patients of the Mara Hospital (Bethel Epilepsy Centre) were evaluated. Generalized estimating equation (GEE) models were used for statistical analyses. Results: GEE analyses showed that LCM trough serum concentrations were significantly correlated with the body weight-normalized LCM dose (range: 0.44-25.7 mg/kg; 45-1050 mg) and significantly dependent on comedication and age. Compared with adults (18-60 years), the LCM trough serum concentrations of children aged 6-12 years and children younger than 6 years were significantly lower (-21% to -38%, respectively) and those of elderly patients (. 60 years) were significantly higher (+20%). Sex had no significant influence. Carbamazepine, phenytoin, primidone, phenobarbital, and methsuximide decreased LCM trough serum concentrations significantly by 30%, 32%, 34%, 39%, and 41%, respectively, whereas other AEDs (eg, oxcarbazepine, eslicarbazepine acetate, valproate) had no significant or only a minor impact (zonisamide) on LCM trough concentrations. In children, the effect of enzyme-inducing AEDs was more marked. Of note, the number of blood samples (n = 151) of patients younger than 12 (n = 78) was comparatively low. Alternative GEE models confirmed the effect of comedication, whereas the effect of age, especially in children, depended on adjustment of LCM dosage to body weight, body surface area, or approximated volume of distribution. Conclusions: In accordance with previous therapeutic drug monitoring studies, our results confirmed that enzyme inducers reduce the LCM trough serum concentrations by 30%-40%. In children, the effects of comedication are more pronounced but should be confirmed by further studies.