Liquid Chromatographic Methods for the Determination of Vildagliptin in the Presence of its Synthetic Intermediate and theSimultaneous Determination of Pioglitazone Hydrochloride and Metformin Hydrochloride

Two reversed-phase liquid chromatographic (RP-LC) methodsare described for the determination of two binary mixtures of hypoglycemic agents. In the first method,vildagliptin (VDG) was determined inthe presence of 3-amino-1-adamantanol(AAD),a synthetic intermediate and impurity of VDG.In the second method, pioglitazone hydrochloride (PGZ) and metformin hydrochloride (MET) weresimultaneously determined in their binary mixture.Chromatographic separation in the two methods was achieved on a Symmetry Waters C18 column (150mm×4.6mm, 5μm).In the first mixture, isocratic elution using a mobile phase of potassium dihydrogen phosphate buffer pH (4.6) -acetonitrile-methanol(30:50:20,v/v/v) at a flow rate of 1 mL min 1 with UV detection at 220 nm was performed. In the second method, isocratic elution based on potassium dihydrogen phosphate buffer pH (4.6)-acetonitrile (60:40, v/v) at a flow rate of 1 mL min 1 with UV detection at 210 nm was performed. Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 5-200 μgmL 1,0.5-3 μgmL 1 and 10-150 μgmL 1 for VDG, PGZ and MET, respectively. The optimized methodswere validated and proved to be specific, robust, precise and accurate for the quality control of the drugs in theirpharmaceutical preparations