Determination of MS-275, a novel histone deacetylase inhibitor, in human plasma by liquid chromatography–electrospray mass spectrometry

A rapid method was developed for the quantitative determination of the novel histone deacetylase inhibitor, MS-275, in human plasma. Calibration curves were constructed in the range of 1–100 ng/ml, and were analyzed using a weight factor proportional to the nominal concentration. Sample pretreatment involved a one-step protein precipitation with acetonitrile of 0.1 ml samples. The analysis was performed on a column (75 mm ×4.6 mm i.d.) packed with 3.5 μm Phenyl-SB material, using methanol—10 mM ammonium formate (55:45 (v/v)) as the mobile phase. The column effluent was monitored by mass spectrometry with positive electrospray ionization. The values for precision and accuracy were always ≤5.58 and <11.4% relative error, respectively. The method was successfully applied to examine the pharmacokinetics of MS-275 in a cancer patient.