Three layered pellets of budesonide were prepared for colon delivery by the extrusion-spheronization method. The coatings consisted of hydroxypropylmethyl cellulose (HPMC) (as barrier layer), Eudragit E (as rate controlling layer) and hydroxypropylmethyl cellulose acetate succinate (HPMC AS) (as enteric layer). The rate controlling layer was further modified using various pore formers. Dissolution studies were carried out at pH 1.2, 7.4 and 6.8. Pellet core composition and type and level of pore former affected the drug release from pellets. Pellets containing 20 % (m/m) citric acid in the cores coated with HPMC at a coating level of 6 % (m/m), Eudragit E containing Avicel RC 581 (30 %) as pore former at a coating level of 30 % (m/m) and HPMC AS at a coating level of 15 % (m/m) had the best release profiles. These pellets showed promising results in alleviating the conditions of an experimental model of colitis induced by trinitrobenzenesulfonic acid in rats.
Preparation and evaluation of a time-controlled release capsule made of ethylcellulose for colon delivery of drugs.
