Bravo-Osuna I, Ferrero C, Jiménez-Castellanos M R
Departamento Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Sevilla, Sevilla, Spain.
Eur J Pharm Biopharm. 2005 Apr;59(3):537-48. doi: 10.1016/j.ejpb.2004.10.003.
A new family of graft copolymers combining hydrophilic and hydrophobic components have recently been proposed as direct compression excipients. Copolymers were synthetised by free radical copolymerisation of starch derivatives with methyl methacrylate (MMA) and were alternatively dried by oven or freeze-drying techniques. The aim of this study was to investigate the water vapour sorption-desorption behaviour of these copolymers, focusing on the influence of variables such as the hydrophobic component and the drying process. Moisture sorption and desorption isotherms were measured at 25 degrees C and analysed according to GAB and Young-Nelson equations, which distinguish between different physical forms of moisture distribution. The Young-Nelson model gave the best fit to the experimental data. The results obtained showed that the presence of the acrylic component modified not only the total hygroscopicity of the copolymers, as compared with the original starch derivatives, but also the water distribution in the solid, which might have an important role in the effect of moisture content on copolymer characteristics. The main water-sorption mechanism seemed to be absorption into the copolymer particles structure, in agreement with their starching nature. In terms of water sorption-desorption characteristics, no marked differences were found between the two drying methods used.
最近有人提出一种结合了亲水性和疏水性成分的新型接枝共聚物作为直接压片辅料。通过淀粉衍生物与甲基丙烯酸甲酯（MMA）的自由基共聚合成共聚物，并分别采用烘箱干燥或冷冻干燥技术进行干燥。本研究的目的是研究这些共聚物的水蒸气吸附 - 解吸行为，重点关注疏水性成分和干燥过程等变量的影响。在25℃下测量水分吸附和解吸等温线，并根据GAB和Young - Nelson方程进行分析，这两个方程区分了水分分布的不同物理形式。Young - Nelson模型对实验数据拟合最佳。所得结果表明，与原始淀粉衍生物相比，丙烯酸成分的存在不仅改变了共聚物的总吸湿性，还改变了固体中的水分分布，这可能在水分含量对共聚物特性的影响中起重要作用。主要的吸水机制似乎是水吸收到共聚物颗粒结构中，这与其淀粉性质一致。就吸水 - 解吸特性而言，所使用的两种干燥方法之间未发现明显差异。
