Evaluation of gum karaya as a carrier in the design of oral controlled-release hydrophilic matrix systems

Gum karaya (GK) was evaluated as a hydrophilic carrier for the preparation of controlled-release matrix systems. The effects of different parameters, such as polymer content, method of matrices preparation, pH, addition of co-excipients and the nature of aqueous solubility of the drug on its dissolution profile have been studied. It was observed that the dissolution profile declined with an increase of the GK content in the matrix system. Matrices prepared by wet granulation showed prolonged dissolution profiles compared to the matrices prepared by direct compression. The in vitro dissolution profile varied with pH conditions. Incorporation of co-excipients in matrix systems enhanced the release rate and modified the release mechanism. The release rate and mechanism were also influenced by the drug aqueous solubility. Matrix systems containing diclofenac sodium (DS) and theophylline produced faster dissolution profiles following an anomalous release mechanism. Flurbiprofen-GK matrices showed a slow release following the super case II transport. It was found that the dissolution profile of DS from DS/GK matrices (1:1, m/m) was comparable with that of the commercial sustained-release product. Both formulations displayed a sustained blood level pattern.