Precipitation of high molecular weight pharmaceuticals by the aerosol solvent extraction system

Dense gas anti-solvents can be used for the recovery of valuable compounds from liquid solutions and also for the separation of solid mixtures. In this study the micronisation of high molecular weight pharmaceuticals such as biodegradable polymers and proteins by the Aerosol Solvent Extraction System (ASES) was investigated. Poly(d,l-lactic-co-glycolic) acid (PLGA), poly(l-lactic) acid (L-PLA), and the protein, lysozyme, were precipitated from acetone, methylene chloride (MC) and dimethyl sulfoxide (DMSO), respectively, by spraying the solutions in dense carbon dioxide (CO2) antisolvent. The effect of various parameters such as pressure and temperature on the characteristics of the precipitated materials was investigated. In general it was found that microspheres of the protein and both the polymers could be produced using a range of operating conditions. The precipitated materials also contained negligible residual solvent and exhibited narrow particle size distributions.