Abstract
The aim of the present study was to develop a simple, sensitive and accurate liquid chromatography-electrospray ionization tandem mass spectrometry (ESI-MS/MS) method for the determination of lixivaptan (LIX) in mouse plasma using vildagliptin as the internal standard (IS). A precipitation procedure was used for the extraction of LIX and vildagliptin from mouse plasma. Chromatographic separation of LIX was achieved using a C-18 analytical column (50 x 2.1 mm, 1.8 mu m) at 25 degrees C. The mobile phase comprised acetonitrile and ammonium formate (10mM, pH 3.1; 40:60, v/v) pumped at a flow rate of 0.3 mL min(-1). A tandem mass spectrometer with an electrospray ionization source was used to perform the assay. Quantification of LIX at m/z 290 -> 137 and IS at 154 -> 97 was attained through multiple reaction monitoring. The investigated method was authenticated following the bio-analytical method of validation guidelines of the US Food and Drug Administration. The developed method showed a good linearity over the concentration range from 5 to 500 ng mL(-1), and the calibration curve was linear (r = 0.9998). The mean recovery of LIX from mouse plasma was 99.2 +/- 0.68%. All validation parameters for LIX were within the levels required for acceptance. The proposed method was effectively used for a pharmacokinetic study of LIX in mouse plasma.