Stability-Indicating RP-HPLC Method Development and Validation for Simultaneous Estimation of Metformin, Sitagliptin and Dapagliflozin Bulk and in Tablet Dosage Form

A stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) approach was developed and validated to simultaneously measure Metformin, Sitagliptin and Dapagliflozin concentrations in tablet dosage forms. Chromatographic separation was accomplished by utilizing a C18 column filled with a mobile phase composed of acetonitrile and phosphate buffer (pH 3.5) in a 65:35 % v/v proportion, delivered at a flow rate of 1.0 ml/min.  Metformin, Sitagliptin and Dapagliflozin exhibited excellent resolution, with retention durations of 4.53 min, 7.31, and 10.65 minutes, respectively. The method proved to be remarkably linear for both drugs over the concentration range of 5 - 25 μg/ml for Dapagliflozin, 50-250 μg/ml for for Sitagliptin and 250-1250 μg/ml for metformin, with correlation values (r) of 0.9993 for Dapagliflozin,  0.9999 for Sitagliptin and 0.9990 for  metformin.  Metformin, Sitagliptin, and Dapagliflozin had limits of detection (LOD) of 0.1966 µg/ml, 0.0318 µg/ml, and 0.0575 µg/ml respectively. The quantification limits were 0.5958 µg/ml, 0.0964 µg/ml and 0.1743 µg/ml respectively. The method exhibited robust performance with low % RSD values, ensuring precision and accuracy. Stability studies revealed that drugs were stable under various stress conditions, with degradation percentages well within acceptable limits. The method that was developed effectively used on commercial tablet formulations, therefore demonstrating its appropriateness for common quality control and stability testing in pharmaceutical analysis.