Zein/diclofenac sodium coprecipitation at micrometric and nanometric range by supercritical antisolvent processing

In this work, the supercritical antisolvent (SAS) process is proposed to coprecipitate zein with diclofenac sodium (a model drug). In the first part of this paper, the proper conditions, in terms of pressure, temperature and concentration, for the attainment of zein microparticles, were detected. At 90 bar, 40 degrees C and 50 mg/mL, microparticles with a mean diameter of 4.19 mu m were obtained. The coprecipitation with diclofenac sodium at different polymer/drug ratio and concentration in the liquid solution was successfully performed and, with the support of the drug release analyses, the coprecipitation mechanisms (both in the case of microparticles and nanoparticles formation) were postulated.