A quantitative LC-MS/MS method for simultaneous determination of deuvortioxetine, vortioxetine and their carboxylic acid metabolite in rat plasma, and its application to a toxicokinetic study

Abstract

A rapid, simple, efficient and stable method based on LC-MS/MS for simultaneous determination of deuvortioxetine, vortioxetine and their carboxylic acid metabolite in rat plasma has been established and validated. Carbamazepine was utilized as the sole internal standard. Protein precipitation was used to extract the analytes and internal standard, which were separated on a Waters Xterra C₁₈ chromatography column (2.1 mm × 150 mm, 5 μm). The mobile phases were methanol and a mixture of 0.1% formic acid and 10 mmol L⁻¹ ammonium formate in water. Chromatographic separation was achieved by using an easy isocratic elution program with 70% of methanol and a flow rate of 0.2 mL min⁻¹. The detection was performed in the multiple-reaction monitoring mode with positive electrospray ionization. The total running time was 5.5 min. Method validation demonstrated that the method was specific, precise, and accurate and showed good linear ranges of 5–1000 ng mL⁻¹ for deuvortioxetine, 5–1000 ng mL⁻¹ for vortioxetine and 25–5000 ng mL⁻¹ for their metabolite, respectively. The precision and accuracy were acceptable, and the lower limit of quantification was identifiable and reproducible at 5 ng mL⁻¹ for both deuvortioxetine and vortioxetine, and 25 ng mL⁻¹ for their metabolite. The plasma samples were stable under different temperature and storage conditions. The method was successfully applied to a toxicokinetic study of deuvortioxetine in rats, which provided important information for further development and application of deuvortioxetine.