Abstract
To determine the necessary technology by which sustained drug release is obtained after drug is delivered to the colon, two kinds of microcapsules were prepared and were filled in a pressure-controlled colon delivery capsule (PCDC). 5-aminosalicylic acid (5-ASA) was microencapsulated with a water-insoluble polymer, ethylcellulose (EC) or with pH-sensitive polymers, Eudragit™ L-100 or S-100 and encased in PCDC, After oral administration of the test preparations to beagle dogs, the first appearance time of 5-ASA into the systemic circulation were 3 hr for all the colon delivery preparations. These test preparations were thought to be delivered to the colon. Both EC microcapsules and Eudragit S/RS microcapsules in PCDC showed longer mean residence time MRT, 8.2±0.6 hr and 8.7±0.9 hr, than Eudragit L/RS microcapsules in PCDC of which MRT was 6.6±0.2 hr, Since PCDC containing 5-ASA powder exhibited a MRT of 7.0±1.0 hr, these two types of preparations have sustained release characteristics.
