A simple HPLC-UV method for the determination of lacosamide in human plasma

Lacosamide (Vimpat®) is an antiepileptic drug approved in the USA, Europe and several other countries as adjunctive therapy for partial-onset seizures. We report a simple HPLC method with UV detection for the quantification of lacosamide in human plasma. The method involves protein precipitation with methanol followed by chromatographic separation using an ACE® C18-AR column (2.1 mm × 150 mm, 3.0 µm) and mobile phases consisting of mixtures of ammonium formate buffer at pH 9 and acetonitrile. Briefly, 25 µl of internal standard and 300 µl of methanol are added to 100 µl of plasma. After vortexing and centrifugation, 70 µl of supernatant is transferred to an autosampler vial and 5.0 µl is injected. Calibration curves are linear in the range of 0.5 to 12.5 µg/ml. A validation was performed that consisted of the evaluation of accuracy and precision, specificity, limit of detection and carryover. Moreover, the possibility of using single-point calibration was evaluated and a crossvalidation between this method and an established LC-MS/MS method using pooled clinical study samples was performed. The method's sensitivity, simplicity and reliance on simpler HPLC equipment should allow for straightforward application in drug monitoring.