High-performance liquid chromatography method for simultaneous determination of the degradation products of metformin hydrochloride and vildagliptin

With the growing production of tablets containing two or more active pharmaceutical ingredients, analytical methods must align with this patient-friendly trend. The development and optimization of a gradient HPLC method for the simultaneous determination of degradation products of metformin and vildagliptin are performed using Full Factorial Design, which allows the significance check of selected factors. Central Composite Design optimizes the method to achieve the desired resolution between critical peak pairs. During the optimization process, the pH and salt concentration in the buffer solution were adjusted, while the oven temperature remained unchanged compared to the initial chromatographic conditions. Separation was achieved using a reversed-phase column. Optimization improved the resolutions between all four critical peak pairs, especially for the critical pair related to vildagliptin. The response surface graphs were used to identify optimal experimental conditions, aligning fully with the optimized method. The aim of this paper is to present the method development and prove that it suits the intended purpose.