Release Behaviors Of Drugs In Polymeric Controlled Release Materials

Recently, the pharmaceutical preparation has been well developed from traditional tablet, injection, capsule to newly drug delivery system (DDS). Drug delivery system can slow down the release velocity of drugs from preparation and extend the efficacy of the drugs. The most important character of this new system is that it can maintain the drug concentration in blood for a long time, and the time of taking drugs can be reduced. Therefore, DDS can improve the safety, validity, adaptability of drugs. The research on the diffusion property of drugs in controlled release materials is very important and useful, which can guide people to choose suitable control release materials for different drugs. Kownledge the diffusion property of drugs in polymer and their interaction to each other could help to systematically analyze their interaction relationship. Finally, it would help people to choose suitable control release materials for different drugs. In this work, the release behavior of drugs in two kinds of controlled release materials, amorphous polymer and hydrogel, are studied via molecularly dynamics simulation.Chapter 3 discussed the diffusion property of three kinds of drugs, benzene, aspirin and nifedipine, in different scales of poly(lactic acid)-poly(ethylene glycol) (PLA-PEG). There are the two main factors which influenced the diffusion of drugs in polymer matrix: wriggling of the polymer chain and the free volume of the polymer matrix. The results show that the free volume of the polymer matrix does not influence the diffusion of aspirin so obviously as small molecules in polymer matrix when the volume of drugs increases, and the wriggling of the polymer chain start to control the release behavior of drugs. The competition in the two kinds of factors are found when benzene molecules release from PLA-PEG. When the size of the drugs becomes bigger, the diffusion of drugs in the polymer is mainly controlled by the wriggling of the polymer chain.Chapter 4 discussed the diffusion of cholesterol in a regular methacrylate-based hydrogel. The simulation results indicate that the structure of water is enhanced and the diffusion of water is weakened in all kinds of hydrogels. The diffusion of cholesterol is mainly controlled by the mesh size of the hydrogel. Larger mesh size is in favor of the diffusion of the cholesterol.