A validated LC-MS/MS bioanalytical method for the simultaneous determination of dapagliflozin or saxagliptin with metformin in human plasma

An LC-MS/MS method was developed and validated for the simultaneous quantitation of dapagliflozin or saxagliptin with metformin in human plasma. Separation and detection of dapagliflozin (DAP), saxagliptin (SAX), metformin (MET) and their internal standards was achieved on Zorbax C-18 column (50 x 4.6 mm, 5 gm) using acetonitrile: 0.1% formic acid (45:55, v/v) as a mobile phase applying electrospray ionization (ESI) source in positive ion mode. Sequential liquid-liquid extraction and precipitation techniques were used for the extraction due to the difference in the physicochemical properties of drugs. The MS/MS response was linear over the concentration ranges from 5 to 500 ng/ml, 2-50 ng/ml and 10-4000 ng/ml for DAP, SAX and MET, respectively. Precision, accuracy, selectivity, recovery, and stability were within the acceptable limits as FDA guidelines. The method is suitable for further application of pharmacokinetic studies.