Stability-Indicating RP-HPLC Method for Determination of Metformin Hydrochloride and Natglinide in Bulk and Tablet Formulations

A new stability-indicating RP-HPLC method for the determination of metformin hydrochloride and nateglinide in tablets was developed. The chromatographic separation was performed on a C18 column employing 0.05 M potassium dihydrogen orthophosphate (pH 3)- acetonitrile (28:72 v/v) as the mobile phase with UV detection at 216 nm. Under the proposed chromatographic conditions, favourable retention parameters (tr, Rs) were obtained with good symmetry of the chromatographic peaks for the studied compounds. The validation studies performed as per ICH guidelines indicated high degree of accuracy, precision, with good degree of sensitivity and robustness of the proposed method. The drugs were subjected to acidic, alkaline hydrolysis, oxidation, wet heat, dry heat and photo degradation studies. The specificity of the method by forced degradation studies confirmed that the method could effectively separate the drugs in presence of their degradation products, hence it can be regarding as stability indicating.