Abstract
The rapid expansion of supercritical solutions (RESS) is well known as an effective method to manufacture fine particles as long as the target substances can be dissolved in supercritical CO2. A potential for preparation of pharmaceutical microcapsules by RESS was investigated in this study. As an example, loperamide hydrochloride and N-Lauroylsarcosine were utilized as the kernel and coating materials, respectively. The drugs were dissolved in small amount of ethanol and chloroform before they were loaded into the supercritical CO2. The experiments showed that the formation of fine particles of loperamide hydrochloride coated with N-Lauroylsarcosine could be completed in a single step by spraying the supercritical solution from 10-20MPa to atmospheric pressure through a 200 µm orifice. The coating effects were observed by a scanning electron microscope. It is found that ratio of the two starting materials greatly affects the final form of products. By optimizing the process parameters, microcapsules have been produced. The typical microcapsules consist of the kernel particle of about 4µm diameter with the coating layer of 1-2 µm thickness. The experimental result indicates that the rapid expansion of supercritical solutions can be a possible way for synthesis of composite microparticles of drugs.
