A Rapid and Sensitive Reversed Phase Liquid Chromatography-Tandem Mass Spectrometry Method For Quantification Of Doxazosin Mesylate In Human Plasma Using Doxazosin Mesylate D8 As Internal Standard

Abstract

A simple, accurate, precise and specific high performance liquid chromatography mass spectrometric method for the estimation of doxazosin in human plasma (K2EDTA), using doxazosin D8 as an internal standard was developed and validated. The samples are prepared by liquid-liquid extraction method by using tetra butyl methyl ether, followed by freezing and evaporation of the organic solvent. The remaining dry residue is redissolved in mobile phase and analyzed by LC-MS-MS with positive electro spray ionization using the multi reaction monitoring mode. An unisol C18 (150 X 4.6) mm, 5 μm, 100 A° column, a mobile phase composed of acetonitrile and 0.05 % ammonia solution in HPLC grade water with isocratic elution, and a flow rate of 1.000 mL/minute with split ratio 1:1 and the column oven temperature was set 40±2°C. The elution time for doxazosin and internal standard were 2 min. All the parameters were maintained for the study. This method is validated for 0.301 ng/mL to 75.179 ng/mL concentration range. The method is applied for doxazosin plasma levels following single administration of doxazosin mesylate tablets to human in the fed state.