Simultaneous Determination of Metformin and Three Gliptins in Pharmaceutical Formulations Using RP HPLC: Application to Stability Studies on Linagliptin Tablet Formulation

Objective: A simple, rapid and validated liquid chromatographic method has been developed for the simultaneous determination of three novel Gliptins namely Vildagliptin (VLD), Sitagliptin (SIT) and Linagliptin (LIN) in their binary mixture with Metformin (MET). Methodology: The separation was performed on fast monolithic column using isocratic, mobile phase consisting of mixture of sodium dihydrogen phosphate, Sodium dedosyl sulphate and acetonitrile. The flow rate was 2.5 mL/min and UV detection for MET, VLD and SIT was conducted at 208 nm, whereas, that of MET and LIN was at 228 nm. The incipiently developed method was subjected for validation according to ICH guidelines. Results: The calibration curves of analytes showed good correlation (r2>0.999) over a concentration range 10–100 μg/mL and 50–400 μg/mL for Metformin, 1–10 μg/mL for Vildagliptin & Sitagliptin and 0.25–2.0 μg/mL for Linigliptin. Conclusion: All three tablet formulations were assayed with accuracy and precision and without interference from excipients. The method is also stability indicating with respect to Linagliptin.