Formulation and Evaluation of Metformin Hydrochloride Sustained Release Tablets Using Polyelectrolyte Complexes

Abstract

The present study involves formulation and evaluation of sustained release tablets of metformin hydrochloride which is BCS Class-III drug, using polyelectrolyte complexes of gum karaya-chitosan. Formulations were prepared by direct compression method and the optimized formulations were prepared as tri layered tablets using HPMC K100M and PECs for desired release. All formulations were evaluated for various precompression parameters like angle of repose, bulk density, tapped density, compressibility index, Hausner's ratio. The drug and excipients compatibility study was performed by Fourier Transformer Infrared Spectroscopy analysis, Powder X-Ray diffraction analysis and Differential scanning calorimetry. The compressed tablets were evaluated for physicochemical parameters like weight variation, thickness, hardness, friability, drug content and in vitro dissolution studies. Results indicated that the pre formulation parameters were within the limits and there was compatibility between the drug and excipients. Results show that as the concentration of PECs was increased the drug release from the matrix tablet was decreased. Initial release from the matrix tablet was 67%. To reduce the release, tri layered tablets were prepared using HPMC K100M and PECs. Initial release was controlled to 25-26%. MH14 and MH16 were considered as optimized formulations and the drug release at 12 th h is 97.26% and 96.27% respectively. The regression coefficient values and the "n" values for optimized formulations were 0.986 and 0.983 indicating zero order release and 0.517 and 0.529 indicating an anomalous transport mechanism. The optimized formulation subjected to stability was found to be stable for one month as per ICH guidelines for climate zone III.