Abstract

FORMULATION AND EVALUATION OF CONTROLLED RELEASE MATRIX TABLETS OF GLIPIZIDE USING DIFFERENT VISCOSITY GRADES OF GUAR GUM

Rama Rao Tadikonda* and Satyanarayana Sreemantula

ABSTRACT

Guar gum, in various viscosity grades, was evaluated as a carrier in the form of hydrophilic matrix for oral controlled drug delivery. Water insoluble glipizide was chosen as a model drug. Glipizide hydrophilic matrix tablets using different proportions of various viscosity grades of guar gum were prepared by wet granulation method and subjected to in vitro drug release studies. Matrix tablets of glipizide containing either 20% low viscosity (GLV-20), 30% medium viscosity (GMV-30) or 30% high viscosity guar gum (GHV-30) were found to provide a controlled delivery when compared with that of commercial SR glipizide tablets (G-CSR). When the data obtained from the in vitro dissolution studies of glipizide matrix formulations and glipizide commercial SR formulation was fitted to drug release kinetics, the correlation coefficients for zero order rates and first order release rate constants of glipizide from guar gum matrix tablets were found almost the same. The diffusion exponents (n = 1.11 to 1.59) indicated that the glipizide release from guar gum matrix tablets followed zero order kinetics by super case II transport mechanism. DSC studies indicated no possibility of drug interaction with guar gum or other excipients used in the preparation of matrix tablets. Stability studies carried out on glipizide matrix tablets showed no evidence of instability indicating a minimum shelf life of 2 years.

Keywords: Controlled release, Glipizide, Low-viscosity guar gum, Medium-viscosity guar gum, High-viscosity guar gum, Matrix tablets.