| Controlled drug delivery systems (CDDS) offer numerous advantages compared to conventional dosage forms including improved efficacy, reduced toxicity and release can be controlled. The properties of polymer matrix and drug have an important effect on the drug release rate as well as their blending. The environment such as the temperature and pH will be affected to the release rate. We known that the drug matrix is polymer and their properties will change when they blending. The compatibility of polymer has an important effect on blending. There are often properties what the single polymer doesn't possess.The cellulose/poly(ethylene glycol) membrane which prepared by the experiment have a good compatibility, their entropy change is related to the content of the cellulose and have inverse ratio to it. Phase change materials can control the temperature, so Applying DSC method to estimate the Tr for cellulose/poly(ethylene glycol) blend, results showed that this blend's Tr is strongly influenced by the ratio of these two components, and this Tr was generally reduced with the increase of the cellulose percent in blend. According to DSC results, a model wasdeduced that might be available to describe above mentioned regulation between the ratio of two polymer components and blend's Tr such as Tr=A-B*Ln(Wceii/WpEG). In eq., the symbols of WCeii and WPEG represent weight of cellulose and PEG respectively, "Ln" is the natural logarithm. "A" and "B " represent two constants respectively.The cellulose/poly(ethylene glycol)(PEG) blending membrane will have a highly value in medicine when their proportion is 70/30 in quality. By blending two common drugs, vitamin C and Captopril, with cellulose/poly(ethylene glycol) to prepare two drug membrane, and using electricity conductivity to study its drug release behavior and dynamics in vitro. At the same time this paper also study the release effect by the ratio of solid to liquid, pH and temperature, respectively.It can be found that the primary releasing reaction of the drug membrane is very complex during the drug releasing. At present the release pharmacodynamics models of blend drug membrane including one of the zero order, first order and second order equations, and there are many imaginary conditions in these models. As result, such models will bring bigger error and their limitations are obvious exist, they will not able to describe correctly the articulated behavior of the release phenomenon. So these models can't reflect the release course accurately. In order to meet the need of the science and industry, it is necessary to obtain a model that could reflect the drug release course accurately andpracticably.This experiment used dynamic conductivity to study the drug release behavior in vitro and reported a new dynamic model. The model pointed out that the release of this drug membrane is zero order reaction mostly, at the same time there are first order and second order reaction. It can bedescribed as — = k0 + kxju + k2ju2, the symbols of k0 >. kx and￡2 dtrepresent the constant of zero ^ first and second order respectively. The constants are summarized in the paper. The advantages of the new model have no presumes and it including zero order, first order and second order. Though the membrane has bigger zero order releasing rate comparing to first order and second order, the new model hasn't neglect others release. Appling multi-order release model to study drug release we can grasp the release rule macroscopically. This model offer us a multi-order release process and can be understood the release course accurately. At the same time, the releasing activation energy can be gained from the new model.LiuDiansenSupervised by Qing shen... |
