Development and Validation of a Method for Simultaneous Estimation of Metformin and Sitagliptin in Human Plasma by LC-MS-MS and Its Application in a Bioequivalence Study.

A simple, sensitive, precise and accurate method for simultaneous estimation of metformin and sitagliptin from human plasma was developed and validated. Samples extracted from plasma using acetonitrile were separated on an SCX column and estimated using API 4000 Mass Spectrometer in the positive atmospheric pressure ionization mode (Turboionspray) by following multiple reaction monitoring transitions for both parent and daughter ions. A linear calibration plot was achieved for both the analytes in the concentration ranges of 10-2,206 ng/mL (for metformin) and 3-800.5 ng/mL (for sitagliptin) prepared in K2EDTA pooled plasma. Mean recovery for metformin was 92% and for sitagliptin was 104.5%. It is a fully validated method and successfully applied for estimation of these drug molecules during biostudies.