Evaluation of guar gum in the preparation of sustained-release matrix tablets

Polymeric hydrophilic matrices are widely used for controlled-release preparations. The process of drug release is controlled by matrix swelling or polymer dissolution. It has been shown that the swelling of guar gum is affected by concentration of drug and viscosity grade of the polymer. This study examines the mechanism of behavior of guar gum in a polymer-drug matrix. The swelling action of guar gum, in turn, is controlled by the rate of water uptake into the matrices. An inverse relationship exists between the drug concentration in the gel and matrix swelling. This implies that guar gum swelling is one of the factors affecting drug release. The swelling behavior of guar gum is therefore useful in predicting drug release.