pH dependent

The assumption on colon-specific drug delivery system suffers from minor inherent problems. The development of novel into pH dependent and microbially triggered compression enteric  coated  tablets  was  done.  Capecitabine was used as a model drug. The core tablet was coated with acid soluble coating, Eudragit®S-100 which was compression coated with immediate release blend of drug containing microbial triggering polysaccharide, guar gum. Different combinations of polymers were selected to achieve drug targeting to the colon for the treatment  of  colorectal cancer. The novel – CODES successfully showed resistance to the gastric environment and exhibited no drug release in simulated intestinal fluid. In-vitro release studies for prepared  tablets  were carried out for 2 hours in 0.1 N HCl, 3 hours in pH 7.4 phosphate buffer and remaining in 6.8 pH phosphate buffer. In vitro studies revealed that it have limited drug release in stomach, small intestine and released maximum drug in the colonic environment.

The aceclofenac sodium loaded calcium alginate (CA) based microbeads prepared by ionotropic external gelation technique with calcium chloride as cross-linking agent. Calcium alginate microbeads represent a useful tool for oral sustained/ controlled drug delivery but show several problems, mainly related to the stability, and rapid drug release at higher pH that, in most cases, is too fast due to increase porosity. To overcome such inconveniences, which was to develop CA microbeads coated with xyloglucan (XG) as drug release modifier to improve stability and prolong the drug release. The mean particle sizes of drug-loaded microbeads were found to be in the range 476.45±12 to 765.10 ± 0.22. The drug entrapment efficiency was obtained in the range of 62.24±0.66 to 102.75 ± 0.87.The shape and surface characteristics were determined by scanning electron microscopy (SEM). No significant drug-polymer interactions, physical changes and crystallinity of the drug in the formulations were determined by FT-IR spectroscopy, differential scanning calorimetry (DSC) and X-ray powder diffraction [XPRD]. In-vitro drug release profiles of microbeads were pH dependent and were analyzed by different kinetic models. The mechanism of drug release from microbeads depends on swelling and erosion process resulting CA microbeads was diffusion controlled followed by First order kinetics and whereas CA microbeads coated with XG approaching to near Zero- order kinetics.