Development of a selective and sensitive high-performance liquid chromatography-tandem mass spectrometry assay to support pharmacokinetic studies of LY-487,379 in rat and marmoset.

Drugs modulating the metabotropic glutamate type 2 receptor (mGluR2) activity may have therapeutic benefits in treating a large spectrum of neuro-psychiatric disorders, from schizophrenia to Parkinson's disease, both as a symptomatic therapy and potential disease-modifying paradigm. LY-487,379 is a highly selective mGluR2 positive allosteric modulator that is widely used to study mGluR2 function using experimental animal models. The common marmoset is a small primate that has long been used in neuroscience. However, given its small size and small circulating blood volume, conducting studies to determine the PK profile of LY-487,379 is challenging. We developed and validated a sensitive and selective analytical method that enables quantification of LY-487,379 using a limited volume of plasma (10 μL). The analytical method consists of protein precipitation followed by high-performance liquid chromatography with heat assisted electrospray ionization mass spectrometry (HPLC-HESI-MS/MS). The chromatographic separation was achieved using gradient elution with a mobile phase consisting of acetonitrile and 0.01% formic acid in water on a Thermo Scientific Aquasil C18 analytical column (100 × 2.1 mm I.D., 5 μm) operating at 40 °C and at a flow rate of 300 μL/min. The method displays a linear relationship ranging from 0.2 to 100 ng/mL. Intra- and inter-day relative standard deviations are <1.4% and 7.9%, respectively and the relative error ranged from -6.9 to 9.7%. The method was used to quantify LY-487,379 in both rat and marmoset plasma, and PK parameters were determined after a single subcutaneous dose of 1.0 mg kg-1 in both species and significant differences in Cmax, AUC and T1/2 were observed.