Vigabatrin in dried plasma spots: Validation of a novel LC–MS/MS method and application to clinical practice

• A sensitive LC–MS/MS method for vigabatrin determination in dried plasma spots.
• Derivatization of vigabatrin with propyl chloroformate/n-propanol combination.
• Disk corresponding to just 5 μL of plasma was used for analysis.
• The validated method was applied to samples obtained from epileptic patients.

This paper presents a LC–MS/MS method for the determination of antiepileptic drug vigabatrin in dried plasma spots (DPS). Due to its zwitterionic chemical structure, a pre-column derivatization procedure was performed, aiming to yield enhanced ionization efficiency and improved chromatographic behaviour. Propyl chloroformate, in the presence of propanol, was selected as the best derivatization reagent, providing a strong signal along with reasonable run time. A relatively novel sample collection technique, DPS, was utilized, offering easy sample handling and analysis, using a sample in micro amount (∼5 μL). Derivatized vigabatrin and its internal standard, 4-aminocyclohexanecarboxylic acid, were extracted by liquid-liquid extraction (LLE) and determined in positive ion mode by applying two SRM transitions per analyte. A Zorbax Eclipse XDB-C8 column (150 × 4.6 mm, 5 μm particle size) maintained at 30 °C, was utilized with running mobile phase composed of acetonitrile: 0.15% formic acid (85:15, v/v). Flow rate was 550 μL/min and total run time 4.5 min. The assay exhibited excellent linearity over the concentration range of 0.500–50.0 μg/mL, which is suitable for the determination of vigabatrin level after per os administration in children and youths with epilepsy, who were on vigabatrin therapy, with or without co-medication. Specificity, accuracy, precision, recovery, matrix-effect and stability were also estimated and assessed within acceptance criteria.