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Formation of PVP/nimesulide microspheres by supercritical antisolvent coprecipitation
No full textIn order to improve the bioavailability of poorly water soluble drugs, an effective technique is the coprecipitation of the drug with a hydrophilic polymer. In this work, the coprecipitation of polyvinylpyrrolidone/nimesulide (PVP/NIM) nanostructured microparticles using Supercritical Antisolvent (SAS) was proposed. The effects of the main process parameters, such as polymer/drug ratio, overall concentration, operating pressure and temperature were investigated to identify successful operating conditions for SAS coprecipitation. Microparticles with a mean diameter ranging between 1.7 and 4 μm (calculated in number of particles) were successfully produced; they were characterized using different analytical techniques, to demonstrate the occurred coprecipitation. Precipitation yield was found to be about 100% with respect to the amount of solute dissolved in the starting solution. Drug release analyses revealed that Nimesulide dissolution rate from PVP/NIM microparticles in a phosphate buffered saline solution (PBS) was 2.5 times faster with respect to unprocessed drug. The possible precipitation mechanisms involved in the process were discussed
Coprecipitation of Polyvinylpyrrolidone/β-Carotene by Supercritical Antisolvent Processing
No full textProduction of lysozyme microparticles to be used in functional foods, using an expanded liquid antisolvent process
No full textControl of Powders Morphology in the Supercritical Antisolvent Technique Using Solvent Mixtures
No full textThe supercritical antisolvent process (SAS) has been frequently used to obtain microparticles and
nanoparticles. The fluid dynamics of the process related to the study of the liquid jet in contact with
supercritical carbon dioxide (scCO2) is characterized by a one-phase mixing at supercritical conditions and a
two-phase mixing at subcritical conditions. The transition between the two kinds of mixing can be measured in
terms of amplitude of the corresponding pressure range; some organic solvents, like dimethylsulfoxide
(DMSO) are characterized by a wide pressure range, other solvents, like acetone (AC), by a narrow pressure
range. Generally, microparticles are precipitated by atomization, droplets formation and drying in the transition
range, whereas nanoparticles are precipitated in correspondence of completely developed supercritical
conditions. Mixing a wide-transition solvent, like DMSO, to a narrow-transition solvent, like acetone, the
pressure range of the transition from one-phase mixing to two-phase mixing and, accordingly, the morphology
of the precipitates will change.
In this work, two model compounds were SAS processed from DMSO/AC mixtures: cellulose acetate, which is
slightly soluble in DMSO and freely soluble in acetone with the aim of obtaining microparticles and
polyvinylpyrrolidone (PVP) that is slightly soluble in acetone and freely soluble in DMSO in order to obtain
nanoparticles. In the case of cellulose acetate, well-defined microparticles with a mean diameter of 0.42 μm
were obtained, whereas, for PVP, nanoparticles with a mean diameter of 114 nm were precipitated,
demonstrating that this SAS strategy is successful
Antisolvent micronization of BSA using supercritical mixtures carbon dioxide + organic solvent
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Polymers' ultrafine particles for drug delivery systems precipitated by supercritical carbon dioxide + organic solvent mixtures
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Use of solvent mixtures in supercritical antisolvent process to modify precipitates morphology: Cellulose acetate microparticles
No full textSupercritical carbon dioxide + organic solvent mixtures for the antisolvent micronization of sodium alginate
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