Determination of HS270, a new histone deacetylase inhibitor, in rat plasma by LC–MS/MS—Application to a preclinical pharmacokinetic study

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC–MS/MS) method has been developed and fully validated to determine HS270, a new histone deacetylase (HDAC) inhibitor, in rat plasma using SAHA as the internal standard (IS). After a single step liquid–liquid extraction with acetoacetate, analytes were subjected to LC–MS/MS analysis using positive electro-spray ionization (ESI+) under selected reaction monitoring mode (SRM). The chromatographic separation was achieved on a Hypurity C18 column (50 mm × 2.1 mm, i.d., 5 μm). The MS/MS detection was conducted by monitoring the fragmentation of m/z 392.3 → 100.1 for HS270, m/z 265.1 → 232.1 for IS. The method had a chromatographic running time of 2.5 min and linear calibration curves over the concentrations of 0.5–1000 ng/mL. The recovery of the method was 70.8–82.5% and the lower limit of quantification (LLOQ) was 0.5 ng/mL. The intra- and inter-batch precisions were less than 15% for all quality control samples at concentrations of 1.0, 100.0, and 750.0 ng/mL. The validated LC–MS/MS method has successfully applied to a HS270 pharmacokinetic study after oral doses of 25, 50, 100, 200 mg/kg, and i.v. dose of 5 mg/kg to rats.