| Microcapsules' study in pharmacy research and development which belongs to the third phase, mainly for sustained and controlled release agents and targeted agents, represent the research in pharmaceutical preparations. Acording to forming the basis of the mechanism and conditions into one capsule, microcapsule preparation methods can be broadly divided into three kinds, namely chemical, physical and physico-chemical method. Particulate formulations developed rapidly, in-depth research to speed up the particulate carrier preparation is very important, has become a pharmaceutical research hot spot.The chosen capsule material of the topic is chitosan , which is one natural cationic polymer, in addition to a good biocompatibility, film, and flocculation, mucosal absorption, it also has a lower blood pressure, reduce blood sugar, lowering blood lipids, anti-bacterial, anti-tumor effects, is an excellent drug carrier. The chosen drug of the topic is a model drug 5 - fluorouracil, it belongs to the classical anti-cancer drugs, but the short half-life, toxicity, and patients with poor tolerance should be microencapsulated to overcome the above shortcomings and improve the drug stability and bioavailability.With regard to the preparation of chitosan microcapsules have been reported, but to focus on specific preparation process, the task will be to optimize the preparation process on the basis of, respectively, into a capsule and its mechanism of in vitro release of a preliminary study for the Shell Poly sugar as a carrier material in the pharmaceutical microcapsules specific application to provide a theoretical basis.In this paper, the quantification of 5-fluorouracil was determined by UV spectrophotometry method . The results showed that 5-fluorouracil is of good linearity (r=0.9995) in the range of 2～14μg·ml-1.On the basis of preliminary preexamination, the subject uses various traditional methods to prepare microcapsule. In the methods, after predicting the best preparation conditions with the statistical software Minitab15.0, bathes of fluorouracil- chitosan microcapsule is made through central composite design with chitson as carrier material, fluorouracil as model drug. The shape and the particle diameter of microcapsule are represented with optical microscope, scanning electron microscope, transmission electron microscope and so on. The physical-chemical properties of microcapsule is represented by DSC. The drug loadings and entrapment rate of microcapsule is presented with the ultraviolet analysis method. The release property of microcapsule is presented with in vitro release experiment. The quality of the microcapsule made in the subject is in accordance with the expected target, and the reproduction quality is excellent.The sacculation mechanism model varies with different preparation methods. In the research, the respective physicochemical property of wall materials and drug is discussed. First, the characteristic parameter of chitosan with different specification and different source is determined, which includes the determination of deacetylation degree using the improved two abrupt change potential titration method and the determination of viscosity average molecular weight with the method of viscosimetry. Then, the evaluation of the important factors, such as the concentration of chitosan and the usage of the cross linker is performed.The subject studies those factors which may affect the strength and the release of medicine-carried microcapsule, of which includes chitosan's deacetylation degree, concentration and the pH in the solution of chitosan, the pH in the dissolution media and the encapsulating drug and so on. The subject sets up the determination method of the contents of fluorouracil in the release media and determines the dissolution rate of medicine-carried microcapsule with direct release method. The result showed that the microcapsule is up to the standard by comparing the two indexes--initial burst property and sustained-release property. Curve-fitting through dynamical equation is performed to find that the release of microcapsule can be descript with Weibull equation and the correlation coefficient is very high.In the paper, chitosan medicine-carried microcapsule is made through different ways, and its quality is compliance with design. In the study, the determination method of characteristic parameter is mastered and the evaluation on related influence factors is worked out through the study on its sacculation and in vitro release mechanism. The subject enriches the study on the sustained-release microcapsules delivery system with chitosan as carrier and has huge theoretic meanings and bright prospects.
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