Abstract
In the present research, an attempt was made to develop an efficient pH sensitive colon targeted drug delivery system of Albendazole for local action in proximal colon against trichuriasis (whip worm infections primarily in cecum and proximal colon). Albendazole matrix tablets containing varying proportions of single blends of three pH sensitive polymers; Eudragit S100, Hydroxy Propyl Methyl Cellulose Phthalate HP 55 (HPMC Phthalate HP55), Ethyl cellulose (Etcell), with different threshold pH 7.0, 6.8, 7.2 respectively were prepared by wet granulation technique involving drug polymer ratio studies in 1:1, 1:1.5, 1:2, 1:2.5 ratios. In vitro release profiles of Albendazole was sequentially determined in simulated gastric fluid (SGF), simulated intestinal fluid (SIF) pH 6.8 and simulated colonic fluid (SCF) pH 7.2. The in vitro drug release from matrix tablets containing HPMC Phthalate HP55 and EC polymers showed release of 20-47% of Albendazole in SIF, followed by a burst release in SCF. However, matrix tablets containing polymer blends Eudragit S100 showed that no appreciable drug release occurred in SIF (0-20%). Among them, the formulations with drug polymer ratios 1:2 and 1:2.5 showed a minimal release of drug in SIF 1.3% and 0.27%. The formulation with drug polymer ratio 1:2 was selected as optimized formulation because it showed a maximize release in proximal colon i.e. First 2hrs in SCF and the formulation with drug polymer ratio 1:2.5 showed an extended release up to 3hrs in SCF in turn missing the release in the target site i.e. proximal colon. All the systems were found to be stable with respect to drug content as well as physical changes at 400C and 75% RH. The results suggest that pH sensitive polymer based matrix tablets containing Eudragit S100 in drug polymer ratios 1:2 are potential means to achieve targeted colon drug delivery for effective therapy of Albendazole