Validation and application of a liquid chromatography-tandem mass spectrometric method for the determination of GDC-0879 and its metabolite in dog plasma using solid phase extraction

A liquid-chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of GDC-0879 and its ketone metabolite (M1) in dog plasma to support preclinical toxicokinetic evaluation. The method consisted of solid phase extraction for sample preparation and LC-MS/MS analysis in positive ion mode using electrospray ionization for analysis. D4-GDC-0879 and 13C2-D2-M1 were used as internal standards. A quadratic regression (weighted 1/concentration2) was used to fit calibration curves over the concentration range of 1-1000 ng/ml for both GDC-0879 and M1. The accuracy (%bias) at the lower limit of quantitation (LLOQ) was 12.0% and 2.0% for GDC-0879 and M1, respectively. The precision (%CV) for samples at the LLOQ was 11.3% and 2.6% for GDC-0879 and M1, respectively. For quality control samples at 3.00, 400 and 800 ng/ml, the between run %CV was ≤3.9% for GDC-0879 and ≤2.4% for M1. Between run %bias ranged from 4.6 to 12.0% for GDC-0879 and from −0.8 to 2.7% for M1. GDC-0879 and M1 were stable in dog plasma for at least 44 days at −70 °C.