A solid phase extraction-liquid chromatographic-tandem mass spectrometry method for determination of concentrations of GDC-0941, a small molecule class I phosphatidylinositide 3-kinase inhibitor, to support clinical development

A solid phase extraction (SPE) liquid chromatographic-tandem mass spectrometry (LC-MS/MS) method for the determination of GDC-0941 concentrations in human plasma has been developed and validated to support clinical development. An Oasis MCX 10mg 96-well SPE plate was used to extract plasma samples (50 μL) and the resulting extracts were analyzed using reverse-phase chromatography and mass spectrometer coupled with a turbo-ionspray interface. The method was validated over the calibration curve range 0.500-500 ng/mL with linear regression and 1/x(2) weighting. Within-run relative standard deviation (%RSD) ranged from 1.5 to 11.5%, while the between-run %RSD varied from 0.0 to 4.4%. The accuracy ranged from 96.0% to 110.0% of nominal for within-run and 98.0% to 108.0% of nominal for between-run at all concentrations including the LLOQ quality control at 0.500 ng/mL. Extraction recovery of GDC-0941 was between 79.0% and 86.2%. Stability of GDC-0941 was established in human plasma for 602 days at -70 °C and 598 days at -20°C, respectively, and established in reconstituted sample extracts for 167 h when stored at room temperature. Internal standard normalized matrix factor was 1.1, demonstrating that the use of the stable-labeled internal standard GDC-0941-d(8) effectively compensated observed matrix effect and resulting in no adverse impact on the quality of the data produced. This assay was used for the determination of GDC-0941 human plasma concentrations over a sufficient time period to determine pharmacokinetic parameters at relevant clinical doses.

Species and gender differences in the formation of an active metabolite of a substituted 2,4-thiazolidinedione insulin sensitizer

1. The metabolism of a substituted 2,4-thiazolidinedione (P1) with dual PPARalpha/gamma activity was evaluated in male and female rats, dogs and monkeys. A para-hydroxylated metabolite (M1) with potent PPARgamma-selective agonist, was a major circulating drug-related component in female rats, dogs and monkeys, but not in male rats (M1-to-P1 exposure ratio of <1, 3-5, 5 and 5-11 in male rat, monkey, female rat, and dog, respectively). 2. M1 (%) formed in vitro (5, 53, 57-65, 67 and 67% in male rat, monkey, female rat, dog, and human liver microsomes, respectively), rank ordered with M1 (%) formed in vivo (24-45, 53-57, 78, 75-85%, for male rat, monkey, female rat and dog, respectively, after oral administration of P1). 3. The plasma clearance of M1 was higher in male rats (32 ml min(-1) kg(-1) compared with 6, 7 and 2 ml min(-1) kg(-1) in female rat, male monkey and male dogs, respectively). 4. The low amounts of M1 observed in male rats, with the appearance of products of the cleavage of the propyl group between the phenyl groups was probably due to the presence of the sex-specific CYP2C11, which cleaves P1 at the propyl bridge. None of the CYPs present in female rats cleaved P1 at this site and M1 was only produced by CYP2C6. In humans, only CYP2C8 and the polymorphic CYP2C19 produced M1.