Niwa K, Takaya T, Morimoto T, Takada K
Department of Pharmaceutics and Pharmacokinetics, Kyoto Pharmaceutical University, Japan.
J Drug Target. 1995;3(2):83-9. doi: 10.3109/10611869509059209.
A novel ethylcellulose (EC) capsule which releases drug with a time-controlled fashion has been prepared. This capsule is composed of four parts, drug container, swellable substance, capsule body and cap. At the bottom of the body, micropores are made. As water penetrates through these micropores, the swellable substance such as low substituted hydroxypropyl cellulose (L-HPC) swells. When the cap made of water-insoluble macromolecular substance such as EC cannot persist the swelling pressure, the EC cap disintegrates and the drug in the container is released from the capsule. The lag-time is utilized for the delivery of drug to the colon. The release time of the drug from the capsule was measured both in vitro and in vivo experiments. In the case of an in vitro experiment, after 12mg of fluorescein as a model drug and 238mg of starch were filled into the container, caps having different thickness were attached to the capsule body and release study was performed. The release time of the drug was mainly dependent on the thickness of the cap. Using test capsules of which mean cap thickness were 39.1 +/- 2.3 (SE)microns, 63.1 +/- 5.0 microns and 75.6 +/- 4.1 microns, the in vivo release time was estimated after administration to beagle dogs. As a parameter, the peak time (tmax) when plasma fluorescein concentration reached to its maximum level was determined for the estimation of the release time of the drug from the capsule in the gastrointestinal tract. The in vivo tmax was well correlated with the cap thickness.(ABSTRACT TRUNCATED AT 250 WORDS)
制备了一种能以时间控制方式释放药物的新型乙基纤维素（EC）胶囊。该胶囊由四部分组成，即药物容器、可膨胀物质、胶囊体和胶囊帽。在胶囊体底部制有微孔。当水通过这些微孔渗透时，诸如低取代羟丙基纤维素（L-HPC）之类的可膨胀物质会膨胀。当由诸如EC之类的水不溶性大分子物质制成的胶囊帽无法承受膨胀压力时，EC胶囊帽会崩解，容器中的药物就会从胶囊中释放出来。延迟时间用于将药物输送到结肠。通过体外和体内实验测定了药物从胶囊中的释放时间。在体外实验中，将12mg作为模型药物的荧光素和238mg淀粉装入容器后，将具有不同厚度的胶囊帽连接到胶囊体上并进行释放研究。药物的释放时间主要取决于胶囊帽的厚度。使用平均胶囊帽厚度分别为39.1±2.3（SE）微米、63.1±5.0微米和75.6±4.1微米的测试胶囊，在给比格犬给药后估计其体内释放时间。作为一个参数，测定血浆荧光素浓度达到最高水平时的峰值时间（tmax），以估计药物在胃肠道中从胶囊的释放时间。体内tmax与胶囊帽厚度具有良好的相关性。（摘要截取自250字）
