Micronisation of Ethyl Cellulose by Supercritical Anti-solvent Process

Supercritical Anti-Solvent (SAS) process is considered as a clean technology suitable for particle design, micron or nanometer sized. It is generally used to micronize compounds of interest in mild operating conditions of temperature and nearly without any residual solvent traces in the end-product. By varying the process parameters, the properties of the produced powders can be adjusted with a defined size, morphology and a narrow size distribution. There is currently a growing interest for the elaboration of controlled delivery systems. For this purpose, SAS process can be also applied to co-precipitate molecules of interest with biocompatible and/or biodegradable polymers. In this study, SAS process was applied to micronize a biocompatible polymer, Ethyl Cellulose, widely used as a drug carrier in controlled delivery systems for oral administration. Carbon dioxide was used as an anti-solvent while Ethyl acetate, low in toxicity, was used as a solvent under 10 MPa and at 308 K. The influence of the process parameters upon the characteristics of the micronized polymer was evaluated by varying several parameters: the polymer concentration in the organic solution (from 1 up to 4 wt.%), the solvent/CO2 molar ratio (from 5 to 8 mol%) and the capillary tube diameter (127 and 254 μm). Ethyl cellulose particles were produced with a narrow mean distribution, in a range comprised between 0.2 and 2.2 μm.