The gas antisolvent (GAS) process makes use of the ability of gases to dissolve in organic liquids and to lower the solvent power of the liquid for the solutes in solution

thus causing the solids to precipitate.Ethyl-cellulose(EC) is the ramification of cellulose.It is the first time to use the gas antisolvent process to produce EC microparticles

which would be mainly used as a hydrophobic coating material or matrix former for modifying the release of drugs from oral dosage forms.In the experimental conditions

different size particles of EC

with mean diameters ranging from 2 μm to 15 μm

were obtained.Several parameters

such as pressure

temperature and different organic solvents

were investigated.The results showed that the mean particle size increased as the temperature of the particle formation vessel increased;while the particle size and its distribution decreased as the pressure of the particle formation vessel increased.The acetone solution of EC could make smaller particles than the ethanol solution.This work is the first step to make sustained releasing

target

adhesive and drug containing EC micropariticles.