LC-MS/MS Method Development and Validation of Mifepristone and its Metabolites in Human Plasma

A rapid, specific and sensitive liquid chromatography-ESI mass spectrometry method was developed and validated for determination mifepristone and its metabolites in human plasma using levonorgestrel as internal standard. The extraction was performed by solid phase extraction procedure using waters Oasis HLB cartridge (1 cc, 30 mg). The column used was Hypurity C18 column (50 × 4.6 mm, 5 μm), the mobile phase was a combination of methanol water containing 0.2% Acetic acid at a ratio of 75:25 in isocratic mode. The flow rate was 0.5 ml/min with an injection volume of 2 μl and the total run time was 4 min. The detection was performed on a triple guard electron spray ionization mass spectrometry by selective reaction monitoring (SRM) mode. The target ions were monitored at [m+H] + m/z 430.3→134, 416.3→120, 446.3→109.1 for Mifepristone, N-Demethyl Mifepristone and Hydroxy Mifepristone respectively. Linearity was established in the range of 51.89 ng/ml to 4059.14 ng/ml, 51.9063 ng/ml to 4059.69 ng/ml, 12.68 ng/ml to 992.36 ng/ml for the determination of Mifepristone, N-Demethyl Mifepristone and Hydroxy Mifepristone respectively in K3EDTA using solid Phase Extraction procedure. The lower limit of quantification was found and reproducible (LLOQ) at 50.95 ng/ml, 54.11 ng/ml and 12.81 ng/ml for Mifepristone, N-Demethyl Mifepristone and Hydroxy Mifepristone respectively.