A Rapid Liquid Chromatography–Tandem Mass Spectrometry Bioanalytical Method For Quantification Of Gepirone In Rat Plasma Using Lurasidone As An Internal Standard: Method Development, Validation And Pharmacokinetic Application

Abstract

Gepirone is an azapirone antidepressant that acts primarily through partial agonism of serotonin 5-HT1A receptors and has gained renewed attention following its approval for major depressive disorder. This study designed to create a simple and reliable Liquid Chromatography–Tandem Mass Spectrometry procedure for determining gepirone in rat plasma using lurasidone as the internal standard. Chromatographic separation was accomplished on a Zorbax SB C18 column (150 × 4.6 mm, 3.5 μm) under isocratic conditions with methanol and 0.1% aqueous formic acid (40:60, v/v) at a flow rate of 1.0 mL/min. Detection was carried out on a SCIEX QTRAP 5500 mass spectrometer operated in positive ESI and multiple-reaction-monitoring modes. Plasma samples were prepared by protein precipitation, providing a rapid and economical sample-processing approach. The assay was linear over 10–80 ng/mL, with 0.9998 determination coefficient. All validation results satisfied the predefined requirements for selectivity, precision, accuracy, recovery, matrix effect, ruggedness, carryover, dilution integrity, and stability. Gepirone recovery ranged from 96.05% to 97.16%, whereas lurasidone recovery was 97.31%. Mean accuracy during matrix-effect assessment was 96.05% at the low quality-control level and 97.11% at the high quality-control level. The RTs of gepirone and lurasidone were approximately 2.23 and 4.02 min, respectively, within a total analytical time of 7 min. The method was successfully applied to rat plasma samples and provided adequate performance for preclinical PK analysis. Its straightforward extraction, consistent recovery, and reproducible analytical response support its use for routine determination of gepirone in biological samples.