preparation and in vitro evaluation of guar gum based triple-layer matrix tablet of diclofenac sodium

the objective of the present study was to design an oral controlled drug delivery system for sparingly soluble diclofenac sodium (dcl) using guar gum as triple-layer matrix tablets. matrix tablet granules containing 30% (d1), 40% (d2) or 50% (d3) of guar gum were prepared by the conventional wet granulation technique. matrix tablets of diclofenac sodium were prepared by compressing three layers one by one. centre layer of sandwich like structure was incorporated with matrix granules containing dcl which was covered on either side by guar gum granule layers containing either 70, 80 or 87% of guar gum as release retardant layers. the tablets were evaluated for hardness, thickness, drug content, and drug release studies. to ascertain the kinetics of drug release, the dissolution profiles were fitted to various mathematical models. the in vitro drug release from proposed system was best explained by the hopfenberg model indicating that the release of drug from tablets displayed heterogeneous erosion. d3g3, containing 87% of guar gum in guar gum layers and 50% of guar gum in dcl matrix granule layer was found to provide the release rate for prolonged period of time. the results clearly indicate that guar gum could be a potential hydrophilic carrier in the development of oral controlled drug delivery systems.