Determination of Duloxetine in rat plasma for pharmacokinetic study by developing a highly sensitive method using liquid chromatography-electrospray ionization tandem mass spectrometry

Abstract

A high sensitive, accurate, rapid assay method has been developed and validated for the estimation of duloxetine in rat plasma with liquid chromatography coupled to tandem mass spectrometry with electro spray ionization in the positive-ion mode. The assay procedure involves extraction of duloxetine and phenacetin (internal standard, IS) from rat plasma by protein precipitation method. Chromatographic separation was achieved using a binary gradient using mobile phase acetonitrile and 0.2% formic acid in water delivered at flow rate of 0.50 mL/min on an Atlantis ODS column with a total run time 4.5 min. The MS/MS ion transitions monitored were 298.4 ➔ 154.1 for duloxetine and 180.2 ➔ 110.1 for IS. As per FDA guidelines, method validation and sample analysis were performed and the results met the acceptance criteria. The linearity was obtained over the concentration range of 0.027 to 1072 ng/mL and the lower limit of quantitation achieved was 27 pg/mL. The intra-day and inter-day precisions were in the range of 1.19-9.51 and 1.98-7.60%, respectively. This method was successfully applied to pharmacokinetic study of duloxetine in rats.