Abstract

Modified guar gum was used as a matrixing agent to develop sustained-release tablets of diltiazem hydrochloride. Modified guar gum was a combination of guar gum and lactic, citric, or tartaric acid. The lactic acid modified guar gum exhibited improved swelling characteristics at pH 1.2 and 7 as compared to that of the untreated guar gum. Seven formulations were prepared according to the simplex lattice design. The amount of modified guar gum, untreated guar gum, and dicalcium phosphate dihydrate were chosen as independent variables. The time required for 80% drug dissolution (t80) in distilled water was selected as the dependent variable and a response equation with interaction terms was generated. A mathematical model was evolved to describe the dissolution profile using log time as an additional independent variable. The kinetics of drug release is explained by Korsemeyer and Peppas model.