Development and Validation of a Sensitive LC-MS/MS Assay of GT-14, a Novel Giα2 Inhibitor, in Rat Plasma, and its Application in Pharmacokinetic Study

A sensitive and selective LC–MS/MS method was developed and validated for the quantitation of a novel Gαi2 inhibitor, GT-14, in rat plasma using a SCIEX 6500+ triple QUAD LC-MS system equipped with an ExionLC UHPLC unit. GT-14 (m/z 265.2 → 134.1) and griseofulvin (Internal Standard, IS) (m/z 353.1 → 285.1) were detected in a positive mode by electrospray ionization (ESI) using multiple reaction monitoring (MRM). The assay was linear in the concentration range of 0.78 - 1000ng/mL in rat plasma. Both accuracy and precision values were within the acceptance criteria of ±15%, as established by FDA guidance. The matrix effect was negligible from plasma, with signal percentages of 98.5-106.9%. The mean recovery was 104.5%, indicating complete extraction of GT-14 from plasma. GT-14 was found to be stable under different experimental conditions. The validated method was successfully applied to evaluate plasma protein binding and in vivo pharmacokinetics of GT-14 in rats.