Water uptake and drug release behaviour of drug-loaded compacts prepared from different grades of ethylcellulose

The compacts were directly compressed from different grades of ethylcellulose (EC) with or without sodium diclofenac. The water uptake and drug release behaviour of these compatcs were evaluated in distilled water. The correlation between the release kinetics and water uptake rate of EC compacts was explored. The results indicate that the larger the particle size of the EC powder used, the higher the water uptake of drug-free the EC compact obtained. Actually porosity of the compact was the major factor influencing water uptake. The same result was also found with drug-loaded EC compacts, but the solubility of sodium diclofenac, the porosity and disintegration EC compacts might be responsible for drug release. The particle size of EC seemed to have more influence on water absorption than the molecular weight of EC.