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Retinyl acetate (RA) was selected as a model compound to be entrapped in poly(lactic- co-glycolic)acid (PLGA) microspheres using supercritical emulsion extraction (SEE). Several oil-in-water emulsions prepared using acetone and aqueous glycerol (80% glycerol, 20% water) were processed using supercritical carbon dioxide (SC-CO2) to extract the oily phase and to induce microspheres formation. The characteristics of the microspheres obtained by conventional liquid emulsion extraction and SEE were also compared: SEE produced spherical and free flowing microspheres, whereas the conventional liquid-liquid extraction showed large intraparticles aggregation. Emulsion extraction by SC-CO2 technology was tested using two different operation layouts: batch (SEE-B) and continuous (SEE-C). SEE-C was performed using a packed tower to produce emulsion/SC-CO2 contact in countercurrent mode, allowing higher microsphere recovery and process efficiencies. Operating at 80 bar and 36°C, SEE-C produced PLGA/RA microspheres with mean sizes between 3.3 and 4.5 μm with an excellent encapsulation efficiency of 80%-90%. Almost all the drug was released in about 6 days when charged at 2.7% (w/w), whereas only 40% and 10% of RA were released in the same period of time when the charge was 5.2% and 8.8% (w/w), respectively. Release kinetics constants calculated from the experimental data, using a mathematical model, were also proposed and discussed. © 2011 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:4357-4367, 2011 [ABSTRACT FROM AUTHOR]

Supercritical fluid extraction using a high-pressure packed tower is proposed not only to remove the ethanol residue from liposome suspensions but also to affect their size and distribution leading the production of nanosomes. Different operating pressures, temperatures, and gas to liquid ratios were explored and ethanol was successfully extracted up to a value of 400 ppm; liposome size and distribution were also reduced by the supercritical processing preserving their integrity, as confirmed by Z-potential data and Trasmission Electron Microscopy observations. Operating at 120 bar and 38°C, nanosomes with a mean diameter of about 180 ± 40 nm and good storage stability were obtained. The supercritical processing did not interfere on drug encapsulation, and no loss of entrapped drug was observed when the water-soluble fluorescein was loaded as a model compound. Fluorescein encapsulation efficiency was 30% if pure water was used during the supercritical extraction as processing fluid; whereas an encapsulation efficiency of 90% was obtained if the liposome suspension was processed in water/fluorescein solution. The described technology is easy to scale up to an industrial production and merge in one step the solvent extraction, liposome size engineering, and an excellent drug encapsulation in a single operation unit. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3842-3850, 2015 [ABSTRACT FROM AUTHOR]

Abstract: In this work, the supercritical assisted atomisation (SAA) is proposed, for the first time, for the production of topical carrier microsystems based on alginate–pectin blend. Gentamicin sulphate (GS) was loaded as high soluble and hygroscopic antibiotic model with poor flowability. Particularly, different water solutions of GS/alginate/pectin were processed by SAA to produce spherical microparticles (GAP) of narrow size (about 2μm). GS loading was varied between 20% and 33% (w/w) with an encapsulation efficiency reaching about 100%. The micronised powders also showed high flow properties, good stability and constant water content after 90 days in accelerated storage conditions. The release profiles of the encapsulated drug were monitored using vertical diffusion Franz cells to evaluate the application of GAP microsystems as self-consistent powder formulation or in specific fibres or gels for wound dressing. All formulations showed an initial burst effect in the first 6h of application (40–65% of GS loaded), and in particular GAP4 produced with a GS/alginate/pectin ratio of 1:3:1, exhibited the ability to release GS continuously over 6 days. Antimicrobial tests against Staphylococcus aureus indicated that GS antibiotic activity was preserved at 6 days and higher than pure GS at 12 and 24 days for all SAA formulations, especially for GAP1. [Copyright &y& Elsevier]

In this study, a novel preparation method for alginate-based aerogels charged with nonsteroidal anti-inflammatory drugs (NSAIDs) was developed using prilling in combination with supercritical fluid technique. Nanoporous carriers were prepared by laminar jet breakup of drug/alginate solutions or suspensions followed by cross-linking in ethanol or aqueous CaCl2 solutions, water replacement, and supercritical-CO2-assisted drying. A substantial drug loss was observed for highly soluble ketoprofen lysinate, whereas encapsulation efficiency was satisfying for slightly soluble ketoprofen. The tandem technique successfully produced almost spherical aerogels (sphericity coefficient 0.97-0.99) in narrow size distribution with reduced particle shrinkage and smooth surface (surface roughness 1.10-1.13); the internal porous texture of the parent hydrogels was preserved and appeared as a network of nanopores with diameters around 200 nm. Drug release profiles were monitored using a pH change method to evaluate the possible application of the aerogels as fast dissolving NSAIDs formulation. Aqueous cross-linking led to aerogels encapsulating ketoprofen in the amorphous form and with an enhanced burst effect in simulated gastric fluid (75% in 30 min), whereas ethanol cross-linking produced aerogels embedding drug in crystal clusters with slower dissolution rate. The system appears an interesting potential carrier for the fast delivery of slightly soluble drugs in the upper gastrointestinal tract. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:185-194, 2013 [ABSTRACT FROM AUTHOR]