Shihong Li, Ni Yang and Weiyong Li
A sensitive LC/MS/MS method was developed and validated for the identification and quantification Imrecoxib, its hydroxyl metabolites M1 and its carboxyl metabolites M2 in human plasma. Chromatographic separation was performed on a Welch Ultimate XB C18 column (2.1 mm × 50 mm, 5 μm) with a gradient elution of acetonitrile (solvent A) and 0.1% formic acid in water (solvent B). Mass spectrometric analysis was performed on a triple quadrupole mass spectrometer operated in the multiple reaction monitoring (MRM) mode with the transitions of m/z 370.1→236.1 for Imrecoxib, m/z 386.4→326.4 for hydroxyl metabolites M1, m/z 400.3→236.0 for carboxyl metabolites M2 and m/z 244.2→185.1 for agomelatine (internal standard, IS). The total run time was 3.5 min. Standard curve concentrations ranged from 0.5-60 ng/mL for Imrecoxib, 1 to 100 for M1, and 2-800 ng/mL for M2 in plasma. Selectivity, linearity, lower limit of quantification (LLOQ), accuracy, precision, stability, matrix effect and recovery and carry-over effect were evaluated for all analytes. The validated method was applied to support a pharmacokinetic study of simultaneous determination of Imrecoxib and M1 and M2 in 12 Chinese healthy volunteers