Dense gas processing of polymeric controlled release formulations.

Dense gas techniques, which utilize the properties of fluids in the vicinity of their critical points, are of increasing interest in the processing of pharmaceuticals. It is generally known that dense gases can be used for extractions, chromatographic separations and chemical synthesis due to their liquid-like solvation power and gas-like mass-transfer properties. The processes can be conducted at moderate operating conditions and are thus suitable for many heat-labile compounds such as proteins, biocompatible polymers and pharmaceuticals. Recent applications of dense gas techniques include micronization, crystallization of high-purity particles, sterilization and preparation of microencapsulated drug formulations. The following paper provides a brief overview of dense gases and various processing techniques to fabricate polymeric drug-loaded formulations for controlled release purposes.