| Within recent years, there has been considerable research activity within the field of oral colon-specific drug delivery system(OCSDDS). It is designed to target drugs specifically to colon without releasing drugs in the upper gastrointestinal tract. The present study was aimed at developing a colonic release tablet using 5-aminocylic acid as the model drug, according to the pH and time controlled release mechanism.Small intestinal transit is constant at 3-4 hours, and is in independent of the type of dosage form and whether the subject is in the fasted or fed state. Therefore this study controlled the lag time of colonic release tablet at 3-4 hours by coating the core tablet containing organic acid with polyacrylic resin IV. The formulation of the core tablet and polyarylic resin IV coating was studied through full factorial experimental. The result showed as the amount of succinic acid in the core table reduced or as the coating amount of polyarylic resin IV increased, the lag time increased. 10mg succinic acid in the core tablet and 11% polyarylic resin IV coating were chosen as the optimized formulation. Based on the formulation, the HPMC and HPMCP formulations were screened.The result of stability test showed that the 5-ASA colonic release tablet was unstable under high humidity condition, and was stable when exposed to strong light and high temperature. This suggested that 5-ASA be airproofed and reserved in dry places. The three months' accelerated test showed the colonic tablet was stable.The result pharmacokinetic study in healthy beagle dogs showed, compared to the conventional tablet, the drug absorption from the conlonic release tablet is much lower; the drug can't not be determined from blood until 7 hours after administration. This indirectly showed the 5-ASA colonic release tablet could target drugs to colon. |
