Department of Pharmaceutics, Faculty of Pharmacy, Shandong University, 250012 Jinan, China.
J Colloid Interface Sci. 2010 May 1;345(1):46-53. doi: 10.1016/j.jcis.2010.01.029. Epub 2010 Jan 18.
Zein is an alcohol soluble protein of corn origin that exhibits hydrophobic properties. Pseudolatexes are colloidal dispersions containing spherical solid or semisolid particles less than 1 microm in diameter and can be prepared from any existing thermoplastic water-insoluble polymer. The novel plasticized film-coating pseudolatex of zein was studied in formulation of sustained-release tablets containing very water-soluble drug. Film formation of plasticized aqueous dispersion was compared with film forming properties of plasticized organic solvent system (ethanol) of zein. The water vapor permeability (WVP), water uptake and erosion, and moisture sorption were evaluated with free films. The tablets containing metoprolol tartrate as a model drug were used in pan-coating experiments. Aqueous film coatings plasticized with PEG 400 exhibited very low water uptake. No significant difference in WVP, moisture sorption and erosion were found between aqueous films and organic solvent-based films of zein plasticized with PEG 400. The atomic force microscopy (AFM) images on microstructure of films showed that colloidal particle size of zein in the aqueous films was smaller than that observed in the solvent-based films. In addition, the aqueous-based films were more compact and smoother than the respective solvent-based films. The aqueous zein-coated tablets containing very water-soluble drug (metoprolol tartrate) exhibited clear sustained-release dissolution profiles in vitro, while the respective solvent-based film-coated tablets showed much faster drug release. Furthermore, aqueous zein-coated tablets had lower water absorption at high humidity conditions. In conclusion, the plasticized aqueous dispersion (pseudolatex) of zein can be used for moisture resistant film coating of sustained-release tablets containing very water-soluble drug.
玉米醇溶蛋白是一种具有疏水性的玉米来源的醇溶性蛋白，具有疏水性。假胶乳是一种胶体分散体，含有直径小于 1 微米的球形固体或半固体颗粒，可由任何现有的热塑性水不溶性聚合物制备。研究了玉米醇溶蛋白的新型增塑薄膜包衣假胶乳，用于包衣含有极水溶性药物的缓释片剂。比较了增塑水基分散体的成膜性能和玉米醇溶蛋白增塑有机溶剂体系（乙醇）的成膜性能。用自由膜评估了水蒸气透过率（WVP）、吸水率和侵蚀以及水分吸附。使用作为模型药物的酒石酸美托洛尔的片剂用于包衣实验。用 PEG 400 增塑的水性薄膜包衣表现出非常低的吸水率。在 WVP、水分吸附和侵蚀方面，用 PEG 400 增塑的水性薄膜和有机溶剂基玉米醇溶蛋白薄膜之间没有发现显著差异。对薄膜微观结构的原子力显微镜（AFM）图像表明，水性薄膜中玉米醇溶蛋白的胶体颗粒尺寸小于观察到的溶剂基薄膜中的颗粒尺寸。此外，水性薄膜比相应的溶剂基薄膜更致密和平滑。含有极水溶性药物（酒石酸美托洛尔）的水性玉米醇溶蛋白包衣片剂在体外显示出明显的持续释放溶解曲线，而相应的溶剂基薄膜包衣片剂则显示出更快的药物释放。此外，水性玉米醇溶蛋白包衣片剂在高湿度条件下吸收的水分较少。总之，玉米醇溶蛋白的增塑水基分散体（假胶乳）可用于包衣含有极水溶性药物的耐湿缓释片剂。
