COLON SPECIFIC DRUG DELIVERY OF LIQUISOLID PLUG OF SULFASALAZINE BY SINGLE CAPSULE WITH BILAYER COATING

The purpose of this study is to achieve colonic release of anti-inflammatory drug sulfasalazine used in the treatment of inflammatory bowel disease (IBD) to minimise side effects with a novel method of single capsule with bilayer coating. Sulfasalazine is an anti-inflammatory drug which acts topically on the inflamed colon to provide relief. In the present study a time and pH dependent colon targeted system was developed and evaluated. Liquisolid plug (LSP) of poorly water soluble drug sulfasalazine was prepared to enhance its dissolution rate and bioavailability. Sulfasalazine liquisolid plug was filled in acrylic polymer coated capsule. This capsule was subsequently coated with ethyl cellulose + HPMC (combination) and eudragit S 100. The eudragit S 100 prevented capsule disintegration in stomach and combination of ethyl cellulose and HPMC prevented capsule disintegration in small intestine. The design of formulation hence ensured colon targeted delivery of drug, preventing premature drug release in stomach or small intestine and enhanced dissolution rate potentiating probable enhancement in bioavailability. In vitro release studies were carried out in 0.1 N HCl pH 1.2, phosphate buffer pH 7.4 and phosphate buffer pH 6.8 mimicking in- vivo conditions for dissolution. Selected systems showed lag time of 6 h with 93.89 % cumulative release in 17 h. This approach is therefore a promising approach to target the colon for the delivery of sulfasalazine.