Quantitation and pharmacokinetics of 1,4-diamino-2,3-dicyano-1,4-bis (2-aminophenylthio) butadiene (U0126) in rat plasma by liquid chromatography-tandem mass spectrometry

A simple, robust, and rapid LC-MS/MS method was developed for the quantitation of U0126 and validated in rat plasma. Plasma samples (20 mu L) were deproteinized using 200 mu L ACN containing 30 ng/mL of chlorpropamide, internal standard. Chromatographic separation performed on an Agilent Poroshell 120 EC-C-18 column (4.6 x 50 mm, 2.7 mu m particle size) with an isocratic mobile phase consisting of a 70: 30 v/v mixture of ACN and 0.1% aqueous formic acid. Each sample was run at 0.6 mL/min for a total run time of 2 min per sample. Detection and quantification were performed using amass spectrometer in selected reaction-monitoring mode with positive ESI at m/z 381 -> 123.9 for U0126 and m/z 277 -> 175 for the internal standard. The standard curve was linear over a concentration range of 20-5000 ng/mL with correlation coefficients greater than 0.9965. Precision, both intra- and interday, was less than 10.1% with an accuracy of 90.7-99.4%. No matrix effects were observed. U0126 in rat plasma degraded approximately 41.3% after 3-h storage at room temperature. To prevent degradation, sample handling should be on an ice bath and all solutions kept at 4 degrees C. This method was successfully applied to a pharmacokinetic study of U0126 at various doses in rats.