Synthesis And Properties Of Novel Polyanhydrides

Polyanhydrides have been investigated as an important biomaterial used for short-term release of drugs due to excellent biocompatibility, controlled release characteristics and good pocessability. In 1996, the Food and Drug Administration (FDA) was approved the use of the polyanhydride poly(1,3-bis(p-carboxyphenoxy) propane-co-sebacic acid) ([CPP]:[SA]=20:80, P(CPP-SA)) to deliver the chemotherapeutic agent BCNU for the treatment of brain cancer.1,3-bis(p-carboxyphenoxy)propane (CPP) is one of the most important raw materials for the synthesis of P(CPP-SA), but the yield and purity of products are lower in industrial field. In this paper, CPP with high purity was obtained via novel methods for the further synthesis of P(CPP-SA), and the polyanhydrides were prepared by improved techniques.The intermediate dimethyl esters were prepared using methyl p-hydroxybenzoate and 1,3-dibromopropane as raw materials, and then hydrolysis of esters were carried out to yield CPP. The purity of products arrived to 99%, and the product yield was up to 83% which was two times more than that obtained via traditional synthesis method (below 40%).Polyanhydrides were prepared using CPP and SA via one pot synthesis. The inherent viscosity of P(CPP-SA) (20:80) was up to 0.56 dL/g. It was degraded in phosphate buffer solution (PBS) for 14 days, and the weight loss was below 76%, which suggested that the polyanhydrides could be used for short-term release of drugs.A series of polyanhydrides, P(CPP-SA) and P(CPP-SA-PEG) were prepared using CPP, SA and PEG prepolymers via two-step method. P(CPP-SA-PEG) was degraded faster in PBS because PEG unites were introduced to improve the hydrophilicity of polymers. Furthermore, the amount of PEG could be used to control degradation period.P(CPP-SA) (50:50) were also synthesized via phase transfer catalysis using different catalysts in the various solvents. The effects of reaction time and the amount of phase transfer catalyst on the inherent viscosity of polyanhydrides were investigated. The polyanhydride with inherent viscosity up to 1.2 dL/g was obtained, and the contolled degradability was observed due to the curves of in vitro degradation. Furthermore, polyanhydrides with active end groups could be developed for other block copolymers.