A Kinetic Study of Poorly Water Soluble Drug Released from Pectin Microcapsules Using Diffusion/Dissolution Model

摘要

A new microcapsular system was developed for the controlled drug delivery from pectins that obtained from various sources, with different molecular weight and the degree of esterification. The release kinetics of poor water soluble drug from the pectin microcapsules was investigated in simulated gastrointestinal fluids using prednisolone as a model drug. The work evaluated the effects of pectin macromolecular characteristics, the nature of surfactant and manufacturing conditions on the release kinetics of encapsulated drugs. The correlation between emulsion systems and drug release profiles was studied through the diffusion/dissolution number, which represents the combination of dissolution and diffusion kinetic parameters in one parameter. The microparticular diffusion coefficients determined by two different kinetics models are much smaller than analogues for other microparticular systems, indicating the critical step of intraparticular diffusion in drug released from pectin microcapsules. The highest value of drug dissolution/diffusion number was obtained for microcapsule from high methoxylated apple pectin in the presence of anionic surfactants and calcium ions, rather than for the systems of highly charged citrus pectin. Capsules prepared by the use of ethyl acetate also showed retarded drug release, however the amount of drug encapsulated was much less than those from other emulsion systems. All the microcapsules had drug release half-life time (t_(50%)) of more then 5 hour. The rapid release of prednisolone was achieved in the presence of pectinase. These results suggested the application of biodegradable pectin polysaccharides in the production of vastly diverse drug carrier systems for colon-specific drug delivery.