Pearnchob Nantharat, Bodmeier Roland
College of Pharmacy, Freie Universität Berlin, Kelchstr. 31, 12169 Berlin, Germany.
Int J Pharm. 2003 Dec 11;268(1-2):1-11. doi: 10.1016/j.ijpharm.2003.07.012.
Pellets were coated with ethylcellulose powder to achieve extended release. The film forming ability of ethylcellulose powder and the effect of formulation factors (plasticizer type and concentration) and curing conditions (curing temperature and time) were investigated. The coating formulation was divided into two components consisting of a powder mixture (polymer plus talc) and a mixture of liquid materials (plasticizer plus binder solution), which were sprayed separately into the coating chamber of a fluidized bed coater (Glatt GPCG-1, Wurster insert). The coated pellets were oven-cured under different conditions (60-80 degrees C, 2-24 h) without and with humidity (100% relative humidity). Propranolol hydrochloride was used as a model drug, and drug release was studied in 0.1 N HCl at 37 degrees C (USP XXV paddle method). Despite the high glass transition temperature of ethylcellulose (133.4 degrees C), micronized ethylcellulose powder can be used for dry powder coating by adjusting the coating temperature, amount and type of plasticizer applied, and curing conditions. 40% plasticizer and a curing step (80 degrees C, 24 h) were required to achieve complete coalescence of the polymer particles and extended drug release of coated pellets. Although ethylcellulose-coated pellets had an uneven surface, extended drug release could be obtained with coating level of 15%. Because of its high glass transition temperature, ethylcellulose-coated pellets showed unchanged drug release profiles upon storage at room temperature for 3 years.
将微丸用乙基纤维素粉末包衣以实现缓释。研究了乙基纤维素粉末的成膜能力以及配方因素（增塑剂类型和浓度）和固化条件（固化温度和时间）的影响。包衣配方分为两组分，一组为粉末混合物（聚合物加滑石粉），另一组为液体材料混合物（增塑剂加粘合剂溶液），将它们分别喷入流化床包衣机（Glatt GPCG - 1，Wurster插入件）的包衣室中。将包衣后的微丸在不同条件下（60 - 80℃，2 - 24小时）进行烘箱固化，有无湿度条件（相对湿度100%）。以盐酸普萘洛尔为模型药物，在37℃的0.1 N HCl中（USP XXV桨法）研究药物释放。尽管乙基纤维素的玻璃化转变温度较高（133.4℃），但通过调节包衣温度、所用增塑剂的量和类型以及固化条件，微粉化的乙基纤维素粉末可用于干粉包衣。需要40%的增塑剂和一个固化步骤（80℃，24小时）来实现聚合物颗粒的完全聚结和包衣微丸的药物缓释。尽管乙基纤维素包衣的微丸表面不均匀，但包衣水平为15%时可获得药物缓释。由于其高玻璃化转变温度，乙基纤维素包衣的微丸在室温下储存3年时药物释放曲线不变。
