Jalil R, Nixon J R
Chelsea Department of Pharmacy, King's College London, University of London.
J Microencapsul. 1990 Apr-Jun;7(2):245-54. doi: 10.3109/02652049009021837.
Poly(DL-lactic acid) (DL-DPA) of three different molecular weights, 20,500; 13,300 and 5200, was used to prepare microcapsules containing differing contents of phenobarbitone (PB), as a reference core. A water/oil (W/O) emulsion evaporation method was used. The effect of polymer molecular weight on the particle size, 'encapsulation efficiency', morphology, density, thermal behaviour and swelling property has been reported. A general trend towards lowering the mean microcapsule size, both by volume and population, was observed with respect to lower polymer molecular weight. The gross morphology of the microsapsule surface, encapsulation efficiency and density were unaffected by variations in polymer molecular weight. Differential scanning calorimetric analysis of the microcapsules showed a lowering of glass transition temperature after microencapsulation. The melting endotherm for phenobarbitone also indicated the presence of crystalline drug in the microcapsule matrix. These microcapsules were found to swell in the aqueous environment and the mean size increased linearly with time. However, the rate of swelling was higher with low molecular weight polymer and also depended on core loading.
使用三种不同分子量（20,500、13,300和5200）的聚（DL-乳酸）（DL-DPA）制备了含有不同含量苯巴比妥（PB）的微胶囊，作为参比核心。采用水/油（W/O）乳液蒸发法。报道了聚合物分子量对粒径、“包封率”、形态、密度、热行为和溶胀性能的影响。观察到随着聚合物分子量降低，平均微胶囊尺寸在体积和数量方面均呈现出降低的总体趋势。微胶囊表面的总体形态、包封率和密度不受聚合物分子量变化的影响。对微胶囊进行差示扫描量热分析表明微囊化后玻璃化转变温度降低。苯巴比妥的熔融吸热也表明微胶囊基质中存在结晶药物。发现这些微胶囊在水性环境中溶胀，且平均尺寸随时间呈线性增加。然而，低分子量聚合物的溶胀速率更高，并且还取决于核心载药量。
