Design and evaluation of a new capsule-type dosage form for colon-targeted delivery of drugs

Study of high amylose corn starch as food grade enteric coating in a microcapsule model system

“…Most of these enteric coatings react to pH changes, and the release of the active core is determined by the local pH in the intestine (Altamn & Dittmer, 1968;Dew, Hughes, Lee, Evans & Rhodes, 1982;Schroeder, Tremaine & Ilstrup, 1987;Ashford, Fell, Attwood, Sharma & Woodhead, 1993;Gazzaniga, Iamartino, Maffione & Sangalli, 1994;Makino, 1994;Gazzaniga, Busetti, Sangalli & Giordano, 1995;Ishibashi, Hatano, Kobayashi, Mizobe & Yoshino, 1998;Marvola, Nykvnen, Rautio, Isonen & Autere, 1999;Pillay & Fassihi, 1999;Krogars et al, 2000;Chittamuru et al, 2001), due to a dramatic increase in the solubility of these polymers that occurs in pH starting at 4.8, and up to 7.2. Since the pH in the small intestine is approximately 6.1-8.0 (Englyst, Anderson & Cummings, 1983) systems, based on these materials, will release the active core compounds in the small intestine and therefore fail to deliver the active substance to the colon.…”

Structure and properties of maize starch processed with a combination of α-amylase and pullulanase

“…Most of these materials are susceptible to pH changes. They release active core compounds in the stomach or the small intestine and not in the colon when a dramatic pH change occurs from 4.8 to 7.2 [5][6][7][8]. Thus, coatings should be based on materials insoluble in both acidic and neutral environments, and capable of resisting pancreatic enzyme digestion.…”

Liberação específica de fármacos no cólon por via oral. II - Tipos de sistemas utilizados

“…Adaptado de Ishibashi et al,1998. mais externo e dissolve-se após o esvaziamento gástrico, tal como a camada intermediária. A cápsula fica reduzida ao revestimento por um polímero ácido-solúvel que se dissolve logo que o pH do micro-ambiente no seu interior diminui, devido à dissolução do ácido orgânico.…”