Wagner Karl, McGinity James
Abt. Pharm. Technologie, Universität Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany.
J Control Release. 2002 Aug 21;82(2-3):385-97. doi: 10.1016/s0168-3659(02)00145-1.
The objective of this study was to investigate the permeability of the cationic acrylic copolymer Eudragit RS 30 D as a function of the anionic buffer species of the dissolution media with special emphasis on the chloride ion exchange of the polymer. Indirect impedance measurement on isolated Eudragit RS films was used to investigate the mechanisms controlling membrane permeability. The chloride ion exchange was determined using capillary electrophoresis during dissolution testing of Eudragit RS 30 D-coated theophylline beads. The dissolution media investigated included various concentrations of sodium acetate, succinic acid and di-sodium succinate. The results of this study demonstrated that the degree of polymer swelling and related drug release was a function of the chloride counterion interaction with the polymer's quarternary ammonium groups. Chloride exchange during the dissolution test with other anions including acetate or succinate ions, resulted in significant changes in the polymer diffusion properties. The ion exchange proved to be the responsible mechanism of controlling polymer permeability as a function of anionic species and concentration. The order of anion permeability enhancing effect was acetate>mono-succinate>disuccinate. The ion exchange could be inhibited significantly by the addition of chloride ions to the dissolution medium.
本研究的目的是研究阳离子丙烯酸共聚物Eudragit RS 30 D的渗透性与溶解介质中阴离子缓冲物质的关系，特别关注聚合物的氯离子交换。通过对分离的Eudragit RS膜进行间接阻抗测量，来研究控制膜渗透性的机制。在Eudragit RS 30 D包衣的茶碱珠粒的溶出试验中，使用毛细管电泳测定氯离子交换。所研究的溶解介质包括不同浓度的醋酸钠、琥珀酸和琥珀酸钠。本研究结果表明，聚合物的溶胀程度和相关药物释放是氯离子与聚合物季铵基团相互作用的函数。在溶出试验中，与其他阴离子（包括醋酸根或琥珀酸根离子）进行氯离子交换，会导致聚合物扩散性能发生显著变化。离子交换被证明是控制聚合物渗透性随阴离子种类和浓度变化的主要机制。阴离子渗透性增强效应的顺序为醋酸根>单琥珀酸根>双琥珀酸根。向溶解介质中添加氯离子可显著抑制离子交换。
