Lavasanifar A, Ghalandari R, Ataei Z, Zolfaghari M E, Mortazavi S A
School of Pharmacy, Shaheed Beheshti University of Medical Sciences, Tehran-Iran.
J Microencapsul. 1997 Jan-Feb;14(1):91-100. doi: 10.3109/02652049709056470.
This study details the process of coating theophylline with ethylcellulose using the coacervation technique of microencapsulation. Microencapsulation of theophylline not only renders it sustained-release, but also decreases its gastric irritation and masks the bitter taste (Lin and Yang 1987). The non-solvent addition method was chosen through a literature survey to ascertain various phases of the coacervate (Robinson 1989, Nixon and Wong 1990). A three-phase diagram was used to determine the optimum quantity of each component required. Steps were then carried out to optimize the production. Drug release rates of the prepared microcapsules were determined over 12-h cycles using the U.S.P. dissolution apparatus and the results obtained were compared with those of Knoll's (Germany) sustained-release theophylline capsules. Significant control over the rate of drug released from the developed dosage form was achieved during the experiment time (12 h). It is concluded that the method employed in this study could be effectively used in the preparation of sustained-release theophylline microcapsules capable of releasing their drug content for an extended period of time. Kinetic studies suggested that both the prepared microcapsules and Knoll's product followed Higuchi's model for drug release. Particle size and release data analysis from five consecutive batches prepared in the laboratory indicated suitable reproducibility of the coacervation process.
本研究详细介绍了采用微囊化凝聚技术用乙基纤维素包衣茶碱的过程。茶碱微囊化不仅使其具有缓释特性，还能减少其对胃部的刺激并掩盖苦味（Lin和Yang，1987年）。通过文献调研选择了非溶剂添加法来确定凝聚相的各个阶段（Robinson，1989年；Nixon和Wong，1990年）。使用三相图来确定所需各组分的最佳量。然后采取步骤优化生产。使用美国药典溶出装置在12小时周期内测定制备的微囊的药物释放速率，并将所得结果与德国Knoll公司的缓释茶碱胶囊的结果进行比较。在实验时间（12小时）内实现了对所开发剂型药物释放速率的有效控制。得出的结论是，本研究中采用的方法可有效地用于制备能够长时间释放药物的缓释茶碱微囊。动力学研究表明，制备的微囊和Knoll公司的产品均遵循Higuchi药物释放模型。对实验室连续制备的五批产品的粒度和释放数据分析表明凝聚过程具有良好的重现性。
