Optimization and pharmacotechnical evaluation of compression‐coated colon‐specific drug delivery system of triphala using factorial design

Abstract

AbstractThe purpose of the present investigation was to achieve successful delivery specifically to the colon using guar gum as a compression coat over a core tablet of triphala. In this study, guar gum along with hydroxy propyl methyl cellulose (HPMC) was used as a compression‐coating polymer. The drug delivery system was based on the gastrointestinal transit time concept, assuming colon arrival time to be 6 h. Rapidly disintegrating core tablets containing 100‐mg triphala extract were compression coated with guar gum and HPMC. A 32 full factorial design was applied for optimization of the formulation. Both variables, the proportion of guar gum in polymer blend (X1) and coat weight of the tablet (X2), had an influence on the percent drug release after 4 h of dissolution of tablet in the presence of rat cecal content (Y240) and difference in percent drug release between 4 h and 10 h of dissolution of tablet in the presence of rat cecal content (YD).The results revealed that for protecting the rapidly disintegrating core of triphala in the physiological conditions of stomach and upper intestine, the core tablet should be coated with 50% of guar gum in coat formulation and higher coat weight. The proportion of guar gum exhibited predominant action as compared to coat weight. In vivo performance was assessed via an x‐ray roentgenography study by placing barium sulfate as an x‐ray opaque material instead of triphala. The guar gum–HPMC coating was found to be a promising drug delivery system for drugs such as triphala and sennosides to be delivered to the colon. Drug Dev. Res. 65:34–42, 2005. © 2005 Wiley‐Liss, Inc.