Formulation Development and in-vitro Evaluation of Sulfasalazine and Dexamethasone Combination Tablets Containing Natural and Semi Synthetic Polymer for Colon Targeting

Abstract

The present research was to develop oral sustained release tablets for colon targeting. Two drugs in combination form were used in this research to prepared tablets. Combination of sulfasalazine and dexamethasone used with natural and semi synthetic polymers (tragacanth and HPMC K15). Sustained release matrix tablets of sulfasalazine and dexamethasone were prepared by using different ratios of drug, HPMC K15 and tragacanth. Microcrystalline cellulose (MCC) and lactose were used as diluents. Both polymers were mixed with other ingredients and formed a matrix system using direct compression technique. All the ingredients of formulation were compressed using concave punches in ZP 19 compression machine. Compressed tablets were evaluated for assay, diameter, hardness, thickness, friability, weight variation and in vitro dissolution using USP dissolution apparatus type II. Different formulations were prepared and evaluated with respect to dissolution profile in 900 mL 0.1 N Hcl and phosphate buffer pH 6.8 and pH7.4 including microbial flora for 12 h at 37˚C. Rising the amount of polymer (HPMC K15) in the formulation led to slow release of drug and decreasing the amount of polymer gave enhanced release of sulfasalazine and dexamethasone. Different mathematical models used to evaluate the matrix system (Zero order, First order, Higuchi and Hixson-Crowell). T5, T7, T8 solid matrix formulations followed zero order and Higuchi. The results showed that the formulation T7 containing 17% HPMC K15 and 17% gum tragacanth gives better results in microbial flora with phosphate buffer. Key words: HPMC K15, Tragacanth gum, Sulfasalazine, Dexamethasone, Sustained release.