Separation of lacosamide, topiramate and levetiracetam by capillary electrophoresis method

Lacosamide (LCM), topiramate (TPM) and levetiracetam (LEV) are novel antiepileptic drugs used to achieve seizure control in patients with epilepsy. In this study, a simple, rapid, and sensitive capillary electrophoresis (CE) method was developed for the simultaneous analysis of LCM, TPM, and LEV. This method was compared with a high performance liquid chromatography (HPLC) method. In the CE method, detection was performed at 210 nm using a photodiode array detector (DAD), and a capillary with an internal diameter of 75 µm and an effective length of 40 cm was employed. Optimum conditions were achieved using a buffer solution consisting of 37 mM SDS, 5 mM borate, and 10 mM phosphate (pH 8.00), applying a potential of 20 kV. The migration times for LCM, TPM, and LEV were determined to be 3.97, 10.62, and 3.61 minutes, respectively. In the HPLC method, detection was carried out using a C18 column (4.6 × 150 mm; 5 µm i.d.). The retention times for LCM, TPM, and LEV were found to be 5.61, 9.17, and 3.61 minutes, respectively. Both developed methods were validated according to the ICH Q2(R2) guidelines. The limits of detection (LOD) and quantification (LOQ) were calculated as follows: for the CE method, 1.03×10⁻⁸ M (0.0025 μg/mL) and 3.13×10⁻⁸ M (0.078 μg/mL) for LCM, 9.17×10⁻⁹ M (0.0031 μg/mL) and 2.78×10⁻⁸ M (0.094 μg/mL) for TPM, and 1.06×10⁻⁸ M (0.0018 μg/mL) and 3.23×10⁻⁸ M (0.0055 μg/mL) for LEV; for the HPLC method, 4.46×10⁻⁸ M (0.011 μg/mL) and 1.35×10⁻⁷ M (0.033 μg/mL) for LCM, 5.16×10⁻⁸ M (0.017 μg/mL) and 1.56×10⁻⁷ M (0.052 μg/mL) for TPM, and 5.32×10⁻⁸ M (0.009 μg/mL) and 1.61×10⁻⁷ M (0.027 μg/mL) for LEV. The developed methods were successfully applied to the analysis of pharmaceutical preparations and were found to comply with the USP 47-NF 42 standards. Keywords: Lacosamide, Topiramate, Levetiracetam, Capillary electrophoresis, High-Performance Liquid Chromatography