Quantitative analysis of enasidenib in dried blood spots of mice blood using an increased sensitive LC-MS/MS method: Application to a pharmacokinetic study.

A simple, sensitive and rapid assay method has been developed and validated as per regulatory guidelines for the estimation of enasidenib on mice dried blood spots (DBS) using liquid chromatography coupled to tandem mass spectrometry with electro spray ionization in the positive-ion mode. The method employs liquid extraction of enasidenib from DBS disk of mice whole blood followed by chromatographic separation using 0.2% formic acid:acetonitrile (25:75, v/v) at a flow rate of 1.0 mL/min on an Atlantis dC18 column with a total run time 2.0 min. The MS/MS ion transitions monitored were m/z 474.0 → 267.1 for enasidenib and m/z 309.2 → 251.3 for the internal standard (warfarin). The assay was linear in the range of 1.01-3044 ng/mL. The intra- and inter-day within-run and between-run precision was in the range of 3.18-9.06 and 4.66-8.69%, respectively. Stability studies showed that enasidenib was stable on DBS cards for one month. This novel method has been applied to analyze the DBS samples of enasidenib obtained from a pharmacokinetic study in mice.