Development and Validation of an UHPLC-MS/MS Assay for the Therapeutic Monitoring of Brivaracetam Plasma Concentrations in Patients with Epilepsy.

Brivaracetam is an antiepileptic drug used as an add-on therapy for partial-onset seizures in subjects aged 4 years and older. Due to potential drug interactions and intersubject variability in plasma concentrations, therapeutic monitoring for brivaracetam may be useful. The aim of this study was to develop a simplified method for measuring brivaracetam plasma concentrations applicable to therapeutic drug monitoring in epilepsy.An ultra high-pressure liquid chromatography-tandem mass spectrometry method was developed and validated according to current guidelines for bioanalytical methods. Sample preparation (100 µL) involved only a simple precipitation step by acetonitrile. Brivaracetam-d7 was used as internal standard. The chromatographic analysis was performed by a Synergi Fusion column using 0.1% formic acid in water/acetonitrile as a binary gradient mobile phase, at a flow rate of 0.3 mL/min. Both brivaracetam and the internal standard eluted at 1.01 minutes. This method was applied to measure trough and 1-hour post morning dose brivaracetam plasma concentrations of 11 patients with epilepsy.The method was validated over a concentration range of 0.10-10 µg/mL. The mean recovery was 95%. Both intra- and inter-assay imprecision and inaccuracy were <15% for all quality control samples. The lower limit of quantitation and detection were 0.10 and 0.05 µg/mL, respectively. No interferences or carry-over was observed. Median (25-75% quartiles) trough and 1-hour post dosing brivaracetam plasma concentrations were 0.61 µg/mL (0.47-0.83 µg/mL) and 1.55 µg/mL (1.24-2.12 µg/mL), respectively, at a median dose of 80 mg/day (50-150 mg/day). Large, up to eight-fold, intrasubject fluctuations of brivaracetam concentrations between trough and 1-hour post dosing were observed.The present assay is faster and simpler than previously published analytical reports for brivaracetam in human plasma and is suitable for therapeutic drug monitoring.