Graves Richard A, Pamujula Sarala, Moiseyev Raisa, Freeman Thomas, Bostanian Levon A, Mandal Tarun K
College of Pharmacy, Xavier University of Louisiana, New Orleans, LA 70125-1098, USA.
Int J Pharm. 2004 Feb 11;270(1-2):251-62. doi: 10.1016/j.ijpharm.2003.10.019.
Two different PLGA samples (Resomer 502 and Resomer 506), either alone or in combinations, were used to prepare microcapsules. Microcapsules were prepared using a double emulsion solvent evaporation technique. The efficiency of encapsulation increased significantly when a mixture of 1 part Resomer 506 and 7 parts Resomer 502 was used to prepare the microcapsules. The efficiency of encapsulation of this batch was 23.7%, whereas the efficiency of encapsulations was only 13.9 and 9.8%, respectively, when the microcapsules were prepared with 100% Resomer 502 or 100% Resomer 506. In contrast, irrespective of the relative ratio of Resomer 502/Resomer 506, the median particle size of the microcapsules showed similar distribution pattern with the median size lies between 49 and 83microm. The glass transition temperature (T(g)) decreased significantly (44.6-25.5 degrees C) as the amount of Resomer 502 was increased in the formulation. The presence of Resomer 502 at lower concentration, along with Resomer 506, initially reduced the "burst effect." However, incorporation of a higher amount of Resomer 502 increased the "burst effect." Drug release from these microcapsules continued over 80 days. In conclusion, efficiency of encapsulation increased significantly when Resomer 506 was mixed with Resomer 502 at a ratio of 1:7. Blending of Resomer 502 with Resomer 506 reduced the glass transition temperature, which resulted in higher amount of drug release throughout the dissolution study.
使用两种不同的聚乳酸-羟基乙酸共聚物（PLGA）样品（Resomer 502和Resomer 506）单独或组合制备微胶囊。采用复乳溶剂蒸发技术制备微胶囊。当使用1份Resomer 506和7份Resomer 502的混合物制备微胶囊时，包封效率显著提高。该批次的包封效率为23.7%，而当用100% Resomer 502或100% Resomer 506制备微胶囊时，包封效率分别仅为13.9%和9.8%。相比之下，无论Resomer 502/Resomer 506的相对比例如何，微胶囊的中位粒径显示出相似的分布模式，中位尺寸在49至83微米之间。随着配方中Resomer 502含量的增加，玻璃化转变温度（T(g)）显著降低（从44.6℃降至25.5℃）。较低浓度的Resomer 502与Resomer 506一起存在时，最初会降低“突释效应”。然而，加入更高量的Resomer 502会增加“突释效应”。这些微胶囊的药物释放持续超过80天。总之，当Resomer 506与Resomer 502以1:7的比例混合时，包封效率显著提高。Resomer 502与Resomer 506的混合降低了玻璃化转变温度，这导致在整个溶出研究中药物释放量更高。
