Chandan Singh Ahirwar, A.K. Pathak
Abstract: The bioavailability of solid drugs and the efficacy of their delivery systems are generally constrained by size, morphology and size distribution. As such these factors controls the solubility of the drugs in the body fluids. The micronization and microencapsulation of drugs with uniform size and uniform morphology are the two methods which requires an efficient novel technologies for producing a system which yields a controlled release of the drugs with enhanced biovailabilty within the therapeutic range. Supercritical fluid has great potential for utilizing it as the solvent or antisolvent in these processes. The fluid is supercritical when it is compressed beyond its critical pressure (Pc) and heated beyond its critical temperature (Tc). The technology has emerged as an important technique for particle manufacturing and has replaced the conventional recrystallization and milling processes mainly because of the quality and purity of the final particles. The remarkable properties of supercritical fluids are considered as continuously adjustable by changing the pressure and temperature to achieve solvating properties with gas and liquid characteristics without actually changing the chemical structure of the compound, that is the physicochemical properties of these fluids are in the intermediate state between gas and liquid, which impart high diffusivity comparable with gas and high solubility as a liquid. Supercritical carbon dioxide as noninflammable, nontoxic, in expensive and due to its mild critical temperature and critical pressure, it is rapidly using fluid for pharmaceutical particle formation, it reveals high solubility for non polar organic compounds but there is a limitation for dissolving polar, ionic or polymeric compounds for which supercritical fluids other than carbondioxide can be used. This review focusses on the characteristics of supercritical fluids, various techniques of paharmaceutical particle manufacturing using supercritical fluids and applications of Supercritical fluid for particle manufacturing.
Keywords: Supercritical fluid, Micronization, Rapid expansion of supercritical solution RESS, Supercritical antisolvent process for particle formation SAS