Introduction: An effective high performance liquid chromatography-tandem mass spectrophotometric (LCMS/MS) simultaneous quantitation of Escitalopram (ESC) and Etizolam (ETZ) in spiked human plasma method was developed. Analytes extraction from plasma was performed by Liquid-liquid extraction (LLE) technique.Materials and Methods: Separation was performed on a Waters symmetry shield, C18 (4.6mm id x 50 mm) analytical column using acetonitrile: 1% formic acid (80:20) v/v with a flow rate of 600μl/min. The MS/MS analysis was performed by multiple reaction monitoring (MRM) to obtain the product ion m/z 325.15 →108.99 for ESC, m/z 343.2 → 138.1 for ETZ and m/z 411.40 →191.30 for internal standard (Risperidone). The obtained calibration curve was linear over the range of 3→2000 ng/ml for both the analytes. Intra and inerday accuracy (% nominal 98 → 102%), precision (% CV ≤4.5%) was excellent. Matrix effect (matrix factor 1.066 for ESC and 1.057 for ETZ), selectivity (% interference = 0) with acceptable extraction recovery (92.75%→98.80%) and stability (% nominal 98.40→101.4%) of different types were reasonable. Conclusion: The proposed method was successfully applied for the pharmacokinetic study of marketed formulation in rabbit blood samples in single oral human equivalents dose. The developed method has further diversified during clinical and preclinical trials in human and other experimental animals.
Keywords: Escitalopram, Etizolam, bioanalytical, LC-MS/MS, pharmacokinetic.