Electrochemical characterization of repaglinide and its determination in human plasma using liquid chromatography with dual-channel coulometric detection

A simple fast and sensitive HPLC method employing dual-channel coulometric detection for the determination of repaglinide in human plasma is presented The assay involved extraction of repaglinide by ethyl acetate and isocratic reversed-phase liquid chromatography with dual-channel coulometric detection The mobile phase composition was 50mM disodium hydrogen phosphate/acetonitrile (60 40 v/v) pH of the mobile phase 7 5 set up with phosphoric acid For all analyses the first cell working potential was +380 mV the second was +750 mV (vs Pd/H-2) Calibration curve was linear over the concentration range of 5-500 nmol L-1 Rosiglitazone was used as an internal standard The limit of detection CLOD) was established at 28 nmol L-1 and the lower limit of quantification (LLOQ) at 85 nmol L-1 The developed method was applied to human plasma samples spiked with repaglinide at therapeutical concentrations It was confirmed that the method is suitable for pharmacokinetic studies or therapeutic monitoring (C) 2010 Elsevier B V All rights reserved