Abstract

The pharmaceutical industry is facing many challenges: Invention of new drugs and improvement of the therapeutic drug efficacy against numerous pathologies, meanwhile supporting a continuous effort to move to environment-friendly processes and reducing the use of potentially harmful solvents. As Nature is almost an unlimited source of active substances, a great interest is paid to concentrate them or to remove undesired compounds, using mainly extraction with organic solvents or water or ethanol/water mixtures, depending on the polarity of the targeted molecules. However, for the past three decades, important R&D works about supercritical fluid technology have been dedicated to natural products processing, leading to some very well-known applications to food products like coffee and tea decaffeination or hops resins extraction, but also to manufacturing phytopharmaceuticals/ nutraceuticals; in fact, carbon dioxide, used pure or added with ethanol, presents the definitive advantages to be a green, abundant and cheap solvent perfectly adequate to process food or pharmaceutical products from natural feed stocks at a temperature near to ambient, although it does require a sophisticated equipment designed for high pressure operation, generally up to 300 or 350 bar. But, natural product needs a natural solvent And for non-polar compounds extraction, there is no alternative to supercritical carbon dioxide. Supercritical Fluid Extraction (SFE) referring to fluid-solid extraction and Supercritical Fluid Fractionation (SFF) - referring to fluid-liquid fractionation are also widely investigated for purification of natural or synthetic active products (for instance, elimination of toxic residues). Moreover, Supercritical Fluid technology is very attractive for manufacturing innovative therapeutic particles, either of pure active compounds or mixtures of excipient and active compounds. In fact, it is important to notice that optimized drug formulation and delivery improve therapeutic efficacy of the drug, reduce adverse effects and bring better comfort to the patient. In comparison to conventional Liquid extraction technique, supercritical fluid extraction is much rapid, due to the low viscosity and high diffusivity of the supercritical fluid. Extraction procedure can be made more selective by controlling the density of the medium. Releasing of the pressure, leads to the change of the phase, that is supercritical fluid returns to the gaseous phase and evaporate, leaving behind the extracted material or constituent. Carbon dioxide is the most widely used supercritical solvent for the extraction procedure.