SIAM STUDIES BY PERFORMING FORCED DEGRADATION OF SITAGLIPTIN AND DAPAGLIFLOZIN USING RP-HPLC

Abstract

Background: A rapid, selective, and stability-indicating reversed-phase high-performance liquid chromatographic (RP-HPLC) method was established for the simultaneous quantification and forced degradation analysis of Sitagliptin phosphate monohydrate and Dapagliflozin propanediol monohydrate in active pharmaceutical ingredients and bulk formulations. Methods: Chromatographic separation was achieved on a Cosmosil C18 column (250 mm × 4.6 mm, 5 µm particle size) using an isocratic mobile phase consisting of methanol and water (60:40 v/v) adjusted to pH 3.0 with orthophosphoric acid. The liquid chromatograph was operated at a flow rate of 0.8 mL/min, an injection volume of 20 µL, a system pressure of 14 to 15 MPa, and an isosbestic detection wavelength of 219 nm. Forced degradation profiling was conducted under basic hydrolytic (sodium hydroxide) and peroxide-mediated oxidative (3% H2O2) stress conditions. Results: Sitagliptin and Dapagliflozin eluted at well-defined retention times of 2.789 minutes and 4.777 minutes, respectively, displaying an inter-analyte chromatographic resolution of 10.045. Column efficiency exceeded 4900 theoretical plates, and USP tailing factors were below 1.16 for both parent analytes. Base hydrolysis of Sitagliptin (2 N NaOH, 80 °C, 1 hour) produced three degradation products (retention times: 6.421, 7.922, and 12.220 minutes), whereas oxidative degradation (3% H2O2, 6 hours) formed a single degradation product (retention time: 5.357 minutes). Dapagliflozin exhibited greater chemical vulnerability, generating four distinct degradation products under alkaline hydrolysis (0.5 N NaOH, 60 °C, 1 hour; retention times: 2.803, 3.589, 6.283, 7.705, and 11.809 minutes) and four degradation products under oxidative stress (retention times: 2.583, 5.875, 7.292, and 10.546 minutes). Complete baseline resolution was maintained between all degradation product peaks and intact parent active drugs. Conclusion: The proposed isocratic RP-HPLC procedure is specific, efficient, and stability-indicating, making it highly suitable for routine quality control, batch release, and degradation analysis of Sitagliptin and Dapagliflozin.