Department of Pharmaceutics, The School of Pharmacy, University of London, 29/39 Brunswick Square, London, United Kingdom.
Eur J Pharm Sci. 2011 Jan 18;42(1-2):30-6. doi: 10.1016/j.ejps.2010.10.003. Epub 2010 Oct 13.
The aim of this work was to understand the influence of polymer interaction and distribution on drug release from microparticles fabricated from blends of polymers. Blends of pH dependent polymer (Eudragit S, soluble above pH 7) and pH independent polymer (Eudragit RL, Eudragit RS or ethylcellulose) were incorporated into prednisolone loaded microparticles using a novel emulsion solvent evaporation method. Microparticles fabricated from blends of Eudragit S and Eudragit RL or RS did not modify drug release compared to microparticles fabricated from Eudragit S alone. This can be attributed to the high degree of miscibility of Eudragit S with Eudragit RS or Eudragit RL within the microparticles as confirmed by glass transition temperature measurements and confocal laser scanning microscopy. In contrast, microparticles prepared from blends of Eudragit S (75%) and ethylcellulose (25%) extended the release of prednisolone at pH 7.4 (compared to Eudragit S microparticles). This change in release profile was related to the immiscibility of Eudragit S and ethylcellulose as assessed by thermal analysis, and confirmed by microscopy which showed pores within the microparticle structures following dissolution of the Eudragit S domains. The ability of water insoluble polymers to extend drug release from enteric polymer microparticles is dependent on the miscibility and interaction of the polymers. This knowledge is important in the design of pH responsive microparticles capable of extending drug release in the gastrointestinal tract.
这项工作的目的是了解聚合物相互作用和分布对由聚合物混合物制成的微球中药物释放的影响。使用一种新的乳液溶剂蒸发方法，将 pH 依赖性聚合物（Eudragit S，在 pH 7 以上可溶）和 pH 不依赖性聚合物（Eudragit RL、Eudragit RS 或乙基纤维素）的混合物掺入到负载有泼尼松龙的微球中。与单独使用 Eudragit S 制成的微球相比，由 Eudragit S 和 Eudragit RL 或 RS 制成的混合物制成的微球并未改变药物释放。这可以归因于通过玻璃化转变温度测量和共焦激光扫描显微镜确认的 Eudragit S 与 Eudragit RS 或 Eudragit RL 在微球内的高度混溶性。相比之下，由 Eudragit S（75%）和乙基纤维素（25%）组成的混合物制备的微球在 pH 7.4 时延长了泼尼松龙的释放（与 Eudragit S 微球相比）。这种释放曲线的变化与通过热分析评估的 Eudragit S 和乙基纤维素的不混溶性以及通过显微镜观察到的微球结构中在 Eudragit S 区域溶解后出现的孔有关。水不溶性聚合物从肠聚合物微球中延长药物释放的能力取决于聚合物的混溶性和相互作用。这一知识对于设计能够在胃肠道中延长药物释放的 pH 响应性微球非常重要。
