A multiple unit system such as pellest of chitosan-SLS coacervates has been investigated for colon-specific delivery using Methylephedrine HCI as a model drug. The drug release experments were carried out in vitro under different conditions to simulate the ph to be encountered during intestinal transit to the colon. The results show the kinetic behavior was controlled by diffusion but not degradating. The addition of chitosan hydrogel solution instead of water as a binding agent during the granulation seemed to yield slower drug release in ph 1.2 medium. The effect of copolymer on retarding release of the drug from prllets in a 0.1N HCI (ph 1.2) conformed to the following order: non-ionic polymer (ex:PVA)>anionic polymer>cationic ploymer.The formation of an insoluble ion complex by chitosan and opposite charge ion was increased the percentage of drug and chitosan release from ph1.2 to ph 6.8 buffer medium. The properties of the composite pellets are suitable for colon targeting. The differential thermal analysis was shown that there is no significant interaction can be observed among the excipients of pellets except adding sodium lauryl sulfate to form coacervate.
