Hydrophilic interaction chromatography–electrospray ionization tandem mass spectrometric analysis of anastrozole in human plasma and its application to a pharmacokinetic study

A hydrophilic interaction chromatography–electrospray ionization tandem mass spectrometric method was developed for determination of anastrozole in human plasma. Anastrozole and irbesartan (internal standard) were extracted from human plasma with a mixture of dichloromethane and methyl tert ‐butyl ether (30:70, v/v). Analysis of the analytes was performed on a Luna HILIC column with the mobile phase of acetonitrile–10 m m ammonium formate (95:5, v/v) and detected by electrospray ionization tandem mass spectrometry in the selected reaction monitoring mode. The standard curve was linear ( r 2  = 0.9992) over the concentration range of 0.10–50.0 ng/mL using 200 μL of plasma sample. The coefficient of variation and relative error for intra‐ and inter‐assay at four QC levels were 1.2–10.0% and −7.2–3.2%, respectively. The present method was applied successfully to the pharmacokinetic study of anastrozole after oral administration of 1 mg anastrozole tablet to healthy male volunteers. Copyright © 2011 John Wiley & Sons, Ltd.