Gangrade N, Price J C
College of Pharmacy, University of Georgia, Athens 30602.
J Microencapsul. 1991 Apr-Jun;8(2):185-202. doi: 10.3109/02652049109071487.
The biodegradable polyesters, poly(hydroxybutyrate) (PHB) and poly(hydroxybutyrate-hydroxyvalerate) (PHBV) were investigated for use as sustained delivery carriers of a model drug, progesterone. Spherical microspheres containing the drug were prepared by an emulsion solvent-evaporation method with gelatin as an emulsifier. Methylene chloride as the polymer solvent yielded smoother microspheres than chloroform. The surface texture was also dependent upon the temperature of the preparation and polymer used. Surface crystals were observed when the drug loading was increased beyond 5 per cent w/w. Thermograms of the microspheres did not show an endotherm corresponding to the melting of the drug because the drug dissolved in the melted polymer while heating. The amount of residual solvent in the microspheres (gas chromatographic assay) ranged from 3.4 to 58.4 ppm and was dependent on the processing temperature, concentration of the polymer in the solvent and the polymer composition. In vitro release of the drug was slowest from microspheres made from copolymer containing 9 per cent hydroxyvalerate. A less porous microsphere matrix was formed by this copolymer.
对可生物降解聚酯聚（3-羟基丁酸酯）（PHB）和聚（3-羟基丁酸酯-3-羟基戊酸酯）（PHBV）作为模型药物黄体酮的缓释载体进行了研究。以明胶为乳化剂，通过乳液溶剂蒸发法制备了含药球形微球。与氯仿相比，以二氯甲烷作为聚合物溶剂可得到更光滑的微球。表面质地还取决于制备温度和所用聚合物。当药物载量增加超过5%（w/w）时，观察到表面结晶。微球的热重曲线未显示出与药物熔化相对应的吸热峰，因为药物在加热时溶解于熔化的聚合物中。微球中残留溶剂的量（气相色谱测定）在3.4至58.4 ppm之间，且取决于加工温度、聚合物在溶剂中的浓度以及聚合物组成。药物从含9%羟基戊酸酯的共聚物制成的微球中的体外释放最慢。该共聚物形成了孔隙率较低的微球基质。
