Correlation Between Efficacy of Levetiracetam and Serum Levels Among Children With Refractory Epilepsy

BackgroundLevetiracetam is used as adjunctive therapy in various types of seizures. Studies evaluating the effect of levetiracetam on children with refractory epilepsy are scarce. The aim of this study was to evaluate the correlation between serum concentration of levetiracetam and either efficacy or tolerability in children with refractory epilepsy, and to determine the value of levetiracetam blood level monitoring.MethodsMedical records of 50 children with refractory epilepsy treated with levetiracetam and regularly followed at Assaf Harofeh Medical Center were retrospectively reviewed. Trough serum levetiracetam concentration was determined using high-performance liquid chromatography and correlated with the administered dose and clinical report.ResultsNo correlation between levetiracetam serum levels and clinical efficacy, tolerability or administered dosage was found. The average dose of levetiracetam was 43.7 ± 20.0 (range 14-100) mg/kg/day and the average serum concentration was 16.0 ± 9.5 (range 2.5-38.5) μg/mL. Forty-five patients (95%) had more than a 50% reduction of seizure frequency, with 22 (44%) patients becoming seizure-free for at least 6 months. Adverse events related to levetiracetam were reported in 15 (30%) patients. No correlation between serum concentrations and adverse events was found. These results were not affected by gender, age, type of seizure, and other drugs.ConclusionsDetermination of serum concentration is not needed in all children treated with levetiracetam. Serum concentrations may be valuable either in patients with refractory epilepsy for compliance evaluation or in patients with satisfactory control of seizures for determination of their therapeutic baseline.