Development and validation of a sensitive HPLC-HESI-MS/MS method for quantitative determination of bitopertin in rat and marmoset plasma

Bitopertin is a potent glycine transporter 1 (GlyT1) inhibitor that has undergone clinical trials for diverse disorders and has a well-documented pharmacokinetic (PK) profile in humans. Even though pre-clinical studies have demonstrated potential therapeutic effects on cognition and neuropathic pain, the PK profile of bitopertin in the rat has been partly disclosed and no study reporting its PK profile in the common marmoset has been published. The aim of this study was to develop and validate a sensitive and selective high-performance liquid chromatography coupled with heat assisted electrospray ionisation tandem mass spectrometry (HPLC-HESI-MS/MS) assay to quantify bitopertin in the rat (Sprague-Dawley) and the common marmoset ( Callithrix jacchus) plasma after administration of 1.0 mg/kg subcutaneously. The analytical method consisted of protein precipitation followed by HPLC-HESI–MS/MS. Chromatographic separation was carried out on a Thermo Scientific Aquasil C18 analytical column (100 x 2.1 mm I.D., 5.0 μm) kept at 50°C using acetonitrile and water both fortified at 0.1% (v/v) with formic acid at a ratio 55:45 as mobile phase with a constant flow rate of 250 μL/min. The calibration function was linear in the range of 0.3-200.0 ng/mL in rat plasma. The intra-day and inter-day precision and accuracy were within ± 15% at all concentrations. The limit of detection (LOD) and quantitation (LOQ) in rat plasma were 0.08 and 0.3 ng/mL, respectively. This method has demonstrated high sensitivity and specificity and was successfully applied to measure bitopertin in rat and marmoset plasma, allowing the investigation of its PK properties in both species.