SEDS Solution Enhanced method

Supercritical anti-solvent micronization can be performed using different processing methods and equipment [17]. Different acronyms were used by the various authors to indicate the micronization process. It has been referred to as GAS (gas anti-solvent), PCA (precipitation by compressed anti-solvent), ASES (aerosol solvent extraction system), SEDS (solution enhanced dispersion by supercritical fluids), and SAS (supercritical anti-solvent) process [8,17]. Since the resulting solid material can be signiflcantly influenced by the adopted process arrangement, a short description of the various methods is presented below. 

SCFs have also been used in conjunction with organic solvents to generate particles of desirec morphology and attributes [56], One intrinsic limitation of SCFs is their inability to dissolve moderate to highly polar compounds. Such compounds can be easily dissolved in suitable organic solvents, and SCFs can be used as antisolvents to precipitate the solids. This procedure has been terme as solution-enhanced dispersion by supercritical Luids (SEDS). Depending on the method by which solution and SCF are introduced and mixed into each other, different applications have been described. These include ... 

Developing coformulations of pharmaceutically active drugs and oligomeric and/or polymeric excipients. The coformulations are usually prepared by the solution-enhanced dispersion by supercritical fluids (SEDS) method. 

The SEDS method was developed by the Bradford University [22,23] in order to achieve smaller droplet size and intensify mixing of supercritical fluid and solution for increased transfer rates. The supercritical fluid is used both for its chemical properties and as spray enhancer by mechanical effect a nozzle with two coaxial passages allow introducing the supercritical fluid and a solution of active substances into the particle formation vessel where pressure and temperature are controlled. The high velocity of the supercritical fluid (Reynolds number in the order of 10 ) allows breaking up the solution into very small droplets. Furthermore, the conditions are setup so that the supercritical fluid can extract the solvent from the solution at the same time as it meets and disperses the solution. 

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