An oral controlled release system based on blends of ethylcellulose and pectin as film-coating material for pellets was developed. Triamcinolone acetonide (TA) as drug useful in intestinal inflammatory disorders was loaded into cyclodextrin-based pellets. The combination of pectin and ethylcellulose as coating materials was investigated in terms of mechanical analysis, viscosimetry, DSC and TGA, water vapor permeability and TA diffusivity using membranes prepared at different ratios. The coating process by fluid bed coating system was used to obtain different thicknesses of coating for pellets previously fabricated by extrusion-spheronization. To investigate the influence of coating on controlled release properties, the microstructure, specific surface area, porosity and TA release profile from pellets were also assayed.

The versatility of the system has been proven by selecting different combinations of blends of polymers. Further, by the reduction in the proportion of pectin in the ethlycellulose:pectin membrane and increasing the thickness of coating, it was possible to achieve a prolonged release over pH 6. These results suggest that the delivery system based on pectin:ethylcellulose coating for pellets has an excellent colon release performance for TA providing protection for drugs that are unstable at acidic pH.

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