Samuelov Y, Donbrow M, Friedman M
J Pharm Sci. 1979 Mar;68(3):325-9. doi: 10.1002/jps.2600680318.
Cast films composed of different ratios of polyethylene glycol and ethylcellulose containing salicylic acid, caffeine, and tripelennamine as model dispersed drugs were prepared and exhibited sustained release. The drug content of the film declined at an apparent first-order rate initially, whereas the drug quantity released was proportional to the square root of time. Data analysis validated the latter treatment, which is in accordance with the diffusional matrix model, and disproved the validity of the apparent first-order conformity. The release rates were independent of film thickness and proportional to drug concentration in pure ethylcellulose films; in polyethylene glycol--ethylcellulose films, a positive deviation from linearity was observed. The logarithm of the rate constant was proportional to the fraction of polyethylene glycol in the film. Unlike in pure ethylcellulose films, the release rate in mixed films was altered by a change in the external fluid pH.
制备了由不同比例的聚乙二醇和乙基纤维素组成的含有水杨酸、咖啡因和曲普利啶作为模型分散药物的铸膜，这些铸膜呈现出缓释特性。膜的药物含量最初以明显的一级速率下降，而释放的药量与时间的平方根成正比。数据分析验证了后一种处理方式，这与扩散基质模型相符，同时否定了明显的一级符合的有效性。在纯乙基纤维素膜中，释放速率与膜厚度无关，且与药物浓度成正比；在聚乙二醇 - 乙基纤维素膜中，观察到偏离线性的正偏差。速率常数的对数与膜中聚乙二醇的比例成正比。与纯乙基纤维素膜不同，混合膜中的释放速率会因外部流体pH值的变化而改变。
