A novel RP-HPLC approach for simultaneous determination of dapagliflozin, linagliptin, and metformin in pharmaceutical formulations

A simple, precise, and stability-indicating reverse-phase high-performance liquid chromatography method was developed and validated for the simultaneous estimation of dapagliflozin, linagliptin, and metformin hydrochloride in fixed-dose combination tablets. Chromatographic separation was achieved using a Phenomenex Luna C18 column (250 × 4.6 mm, 5 μm) with a mobile phase consisting of acetonitrile and phosphate buffer (pH 6.8) in a 40:60 v/v ratio; the buffer was modified to the mentioned pH with triethylamine and orthophosphoric acid. The flow rate was maintained at 0.8 mL/min, with detection at 230 nm. The method demonstrated excellent linearity within the ranges of 20-140 µg/mL for metformin hydrochloride, 0.2-1.4 µg/mL for linagliptin, and 0.6-2.8 µg/mL for dapagliflozin, with correlation coefficients (R²) > 0.995. The validation was performed as per ICH Q2 (R2) guidelines, confirming the method's accuracy, precision (%RSD < 2%), robustness, specificity, and sensitivity. Forced degradation studies under acidic, basic, oxidative, thermal, and photolytic conditions confirmed the method's capability to resolve each analyte from its degradation products, affirming its stability-indicating nature. Application of the method to a commercial formulation yielded assay values of 101.41%, 100.04%, and 99.73% w/w for metformin hydrochloride, linagliptin, and dapagliflozin, respectively. These results validate the method's applicability for routine quality control and stability testing of multi-drug antidiabetic formulations.