Blend of guar gum and Eudragit shows excellent drug release retarding behavior in sustained release tablets

The objective of the current study was to compare sustained release behavior of natural and synthetic polymers in matrix tablets of lisinopril and hydrochlorothiazide combination. Guar gum was used as a hydrophilic natural polymer while Eudragit L 100-55 was used as synthetic polymer. Tablets were formulated by direct compression method using different ratios and combinations of both polymers. Various physical tests were performed. After that, in vitro drug release patterns were investigated by performing dissolution in pH 6.8 phosphate buffer. Results indicated that tablets with combination of both guar gum and Eudragit L 100-55 (foimulation F10) were having the best drug release retarding behavior. All formulations followed zero order kinetics indicating the drug release was independent of the concentration. Higuchi model revealed drug release by diffusion mechanism while Korsmeyer Peppas model suggested that formulations followed the non-fickian release behavior.