Supercritical fluid technology pharmaceutical applications

Supercritical fluid technology has been widely used in extraction and purification processes in the food and pharmaceuticals industryPl 1 1 and for techniques such as supercritical fluid chromatography. Recently, there has been a significant increase in interest of the use of sub- as well as supercritical (SC) carbon dioxide as a substitute for chlorofluorocarbons (CFCs) for a variety of specific and specialized applications t in which the choices of enviromnentally acceptable alternatives are quite limited. 

A number of interesting properties are associated with the critical state. One of these is that the density of the liquid and of the vapor becomes identical, and for this reason the interface between the two phases disappears. Supercritical fluid technology is a relatively new approach to obtain micro- and nanoparticles. For pharmaceutical applications, supercritical carbon dioxide (SC-CO2) is most widely used because of its low and easily accessible critical temperature and pressure (31.2 °C ... 

A new approach in the 1990s was to use supercritical fluid technology to produce uniform particles to replace crystallization. Even though super critical fluids were discovered over 100 years ago, and the commercial plant was built over 20 years ago in the United States, it is only now that the technology is used for a number of pharmaceutical applications (2-5), so as to produce aspirin, caffeine, ibuprofen, acetaminophen, etc. One of the major areas on which the research and development of supercritical fluids is focused is particle design. There are different concepts such as rapid expansion of supercritical solution, gas antisolvent recrystallization, and supercritical antisolvent to generate particles, microspheres, microcapsules, liposomes, or other dispersed materials. 

Supercritical fluid extraction is a new separation technique that finds a number of applications in the natural products, biochemicals, food, pharmaceuticals, petroleum, fuel, and polymer industries (1-8). There is now an interest in applying this technology in the pulp and paper industry (9,10). In a recent comprehensive study on the interaction of supercritical fluids with lignocellulosic materials, it has been shown that lignin can be not only extracted from wood by reactive supercritical fluids but also separated as solid products in solvent-free form by reducing the extraction fluid pressure from a supercritical to sub critical level (11,12). 

Other emerging crystallization techniques, such as supercritical fluid crystallization and sonocrystallization (ultrasound in crystallization), are also mentioned. Potential applications for these emerging technologies are present in the pharmaceutical industry. 

Supercritical Fluid Chromatography (SFQ and Supercritical Fluid Extraction (SFE) A separation technology similar to other extraction and chromatographic methods, but in which the mobile phase is actually a fluid in its supercritical fluid state. A supercritical fluid is a fluid that is held above its critical temperature and pressure, and for which no application of additioncJ pressure can result in the development of a liquid phase. Supercritical fluids are unique in that while they possess liquid-like densities, the mass transfer behavior is superior to that of liquids. Supercritical fluid chromatography remains a niche method that is applicable to pharmaceuticals and other high relative molecular mass solutes. Supercritical extraction, on the other hand, is more widely used as a sample preparation method, especially in pharmaceutical analyses, polymers, and environmental analyses. 

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