title: PLGA microdevices for retinoids sustained release produced by supercritical emulsion extraction: continuous versus batch operation layouts.
abstract: 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.
authors.affiliation: Dipartimento di Ingegneria Industriale, Università di Salerno, Via Ponte don Melillo, 84084 Fisciano (SA), Italy; Laboratorio di Ingegneria Cellulare e Molecolare (DEIS), Università di Bologna, Via Venezia 52, 47521 Cesena (FC), Italy. gdellaporta@unisa.it.
authors.forename: Giovanna Della
authors.initials: GD
authors.lastname: Porta
authors.forename: Roberta
authors.initials: R
authors.lastname: Campardelli
authors.forename: Nunzia
authors.initials: N
authors.lastname: Falco
authors.forename: Ernesto
authors.initials: E
authors.lastname: Reverchon
mesh_terms: D000096:Acetone / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D025924:Chromatography, Supercritical Fluid; D003692:Delayed-Action Preparations; D004224:Diterpenes; D004337:Drug Carriers; D004655:Emulsions; D005990:Glycerol / Q000737:chemistry; D007700:Kinetics; D019344:Lactic Acid / Q000737:chemistry*; D008863:Microspheres; D008956:Models, Chemical; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011312:Pressure; D000084562:Retinyl Esters; D012995:Solubility; D013678:Technology, Pharmaceutical / Q000379:methods*; D013696:Temperature; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D003692:Delayed-Action Preparations; D004224:Diterpenes; D004337:Drug Carriers; D004655:Emulsions; D000084562:Retinyl Esters; D014867:Water; D014801:Vitamin A; D000096:Acetone; D002245:Carbon Dioxide; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C009166:retinol acetate; D005990:Glycerol