Key words: polymer microparticles, encapsulation of bioactive components, sustained release dosage forms, supercritical carbon dioxide
The process of supercritical fluid encapsulation of pharmaceutical grade risperidon into bioresorbable D,L-polylactide microparticles by PGSS (Particles from Gas Saturated Solutions) method is studied. Micronization and change of morphology of risperidon crystals during its encapsulation into polymer plasticized by supercritical carbon dioxide is experimentally observed. This finding enabled fabrication of polymer structures of various dispersion (10—100 μm) and morphologies comprising up to 40 wt.% of risperidon without any use of organic solvent. The kinetics of risperidon release from the polymer microparticles into physiological solution is studied by UV-spectrophotometry. It is shown that the use of different molecular weight D,L-polylactides enables one to extend the risperidon release time from bioresorbable polymer particles fabricated by PGSS up to 10 days in a controllable manner.