Perparation And Application Of The Biodegradable Polymer And Lipisomes Loaded Drugs

Partial sustained drug release for scars comes under an increasingly recognition in medical application. In this article two kinds of drug delivery system were prepared, which were biodegradable poly (D, L-lactic-co-glycolic acid) films implants for sustained release of 5-Fluorouracil, and liposomes encapsulating 5-Fluorouracil aimed for trandermal delivery. The characterization of the drug delivery system was researched respectively, such as the sustained release of the drug, encapsulation efficiency and skin permeation. The main results are as follows:1,Biodegradable PLGA laminar films loaded with 5-FU were prepared by a solvent-casting method. Mw, Mn and the morphology of the films were determined during the polymer degradation. In vitro drug release, zero-order equation and Peppas'equation were respectively used to describe the different phases in 5-FU release from the polymer-films and release parameters were estimated by nonlinear regression analysis. The possible mechanism of 5-FU release from the unmodified and modified polymer-films was proposed. The 5-FU release rate from PLGA implants was regulated by dispersing the films in 23% w/v gelatin solution and PLGA (50:50) solution. The results show the gelatin coated on the films reduced the burst release from 50% to 20% compared with the unmodified films, and the release profile was divided into two parts, the former was controlled by gelatin degradation, the latter followed the Zero-release. Moreover, the films coated by PLGA (50:50) successfully prevented the burst release and the 5-FU release profiles followed the zero-order kinetics within initial 14days. 2,Various particle sizes of Liposomes coating the 5-Fluorouracil or Rodamine B were prepared with thin layer evaporation and reverse phase evaporation method. The transdermal diffusion of the liposomes was investigated in vitro penetration studies into rat skins and human scars. The results are that the particle size of liposomes which were made in thin layer evaporation and reverse phase evaporation were 260±19nm and 130±3nm, respectively. And the stability of the reverse phase evaporation's was better, but the entrapment efficiency was much lower. In vitro, the smaller particle size liposomes could increase the penetration ability of 5-FU into the rat skins and human scars compared with the larger ones.3,5-fluorouracil (5-FU) ethosomes was modified by cholesterol, and the effects of cholesterol on the properties and skin permeation in vitro were investigated. The mean particle size, Zeta potentials, entrapment efficiency, drug permeation rate and amounts of drug in skin of the as-prepared 5-FU ethosomes with different cholesterol amounts were measured. Results showed that the mean diameters of the 5-FU ethosomes were (200±10)nm, the Zeta potentials were almost (-2.7±0.2)mv. And the polydispersity of the 5-FU ethosomes and the entrapment efficiency of 5-FU were obviously improved with the increasing of cholesterol. Moreover, the in vitro experiments indicated that the skin permeation rate and amount of 5-FU accumulation in the skin were dramatically enhanced after modified with cholesterol.