Supercritical Fluid Technology: Nascent Contrivance for Pharmaceutical Product Development

A supercritical fluid (SF) can be defined as a dense non condensable fluid. A fluid reaches the supercritical status when its temperature and pressure exceed the relevant critical temperature and pressure. At the critical point only a single phase exists which has some properties typical of liquids (density) and some of gases (viscosity, compressibility, and mass diffusion coefficient). For pharmaceutical applications, the most widely used SF is carbon dioxide (more than 98% of the applications have been developed using this fluid) because of its low and easily accessible critical temperature (31.2C) and pressure (7.4MPa), non-flammability, non-toxicity and inexpensiveness. The physical and thermal properties of SCFs fall between those of the pure liquid and gas. SCFs offer liquid-like densities, gas-like viscosities, gas-like compressibility properties and higher diffusivities than liquids. The properties of SCFs, such as polarity, viscosity, and diffusivity, can be altered several-fold by varying the operating temperature and/or pressure during the process. This flexibility is enabling the use of SCFs for various applications in the food and pharmaceutical industries, with the drug delivery system design being a more recent addition. INTRODUCTION: The past 20 years have indeed been a remarkable journey for supercritical fluids research, which has been beyond anyone’s initial imaginations. During this time, the application areas continually expanded and experienced an explosive growth. The applications that were initially focused on extraction of natural materials, expanded in a very dramatic way into inorganic materials, polymers, emulsions, biomedical applications, hydrothermal processes, reactions, catalysis, environmental remediation, alternative energy, nanotechnology and hybrid materials. Many of researchers provide different perspectives on particle formation, and co-precipitation processes and their applications in food, pharmaceuticals, cosmetics and drug formulations. Bioavailability of drugs can be enhanced by producing submicron particles via RESS (rapid expansion of supercritical solutions). Co-precipitation techniques allow encapsulation of proteins in biodegradable polymers. PGSS process (particles from gas-saturated solutions) is now a commercial process employed to form powdered lecithin.