Simultaneous Determination of Repaglinide, Metformin hydrochloride and Melamine by New HPLC and HPTLC Chromatographic Methods

Two simple, accurate and reproducible methods have been developed for the simultaneous determination of repaglinide, metformin hydrochloride and melamine in laboratory prepared mixtures, or in dosage forms. The HPLC method used C-18 column (250 x 4.6 mm x 5 & mu;m particle size) and a mobile phase consisting of acetonitrile: methanol: 0.01M Sodium dihydrogen phosphate monohydrate buffer (pH adjusted to 3.00 using o-phosphoric acid) (40:30:30, v/v) at a flow rate of 1 mL/min for 6 min then it was increased to 2 mL /min till 8 minutes, with UV-detection at 242 nm. The HPTLC method used silica gel plate 60 F-254 as stationary phase and chloroform : methanol :acetic acid (8.5:1:0.5, v/v) as developing system .The detection wavelength was 240 nm. The HPLC method was found to be linear through concentration ranges of 1-10 & mu;g/ mL, 2-20 & mu;g/mL and 0.5-10 & mu;g/mL for repaglinide, metformin hydrochloride and melamine respectively. The HPTLC method was found to be linear through concentration ranges of 0.2-1.5 & mu;g/band, 1-10 & mu;g/band and 0.1-1.2 & mu;g/band for the three drugs, respectively. The proposed methods were validated and successfully applied to pharmaceutical formulation containing repaglinide and metformin hydrochloride. The results were statistically compared to a reported HPLC method and no significant differences were found.