Emulsification-solvent evaporation

Watts, P. J., Davies, M. C., and Melia, C. D. Microencapsulation using emulsification/ solvent evaporation An overview of techniques and applications. Crit. Rev. Ther. Drug Carrier Syst. 7(3) 235-259, 1990. 

FIGURE 4 Schematic of microspheres prepared by emulsification/solvent evaporation method. 

Microparticles W/O emulsification solvent evaporation Insulin Chitosan-TBA In rats Improved bioavailability 93... 

Lemos-Senna, E., Wouessidjewe, D., Lesieur, S., and Duchene, D. (1998), Preparation of amphiphilic cyclodextrin nanospheres using the emulsification solvent evaporation method. Influence of the surfactant on preparation and hydrophobic drug loading, Int. J. Pharm., 170,119-128. 

Aquacoat ECD and Surelease are two commercially available ethylcellulose pseudolatex dispersions. Aquacoat ECD. a product of FMC Corporation, is produced by an emulsification/solvent evaporation proce.ss that utilizes sodium lauryl sulfate and cetyl alcohol as colloid. stabilizers (64). The Aquacoat ECD dispersion contains approximately 27% ethylcellulose and 30% total solids. The dispersion does not contain plasticizer, and therefore an appropriate plasticizer must be added to the dispersion prior to coating. The dispersion is typically diluted to a final solids content in the range of 15-20% prior to spray coating. Although, intended to be a pH-independent sustained release coating system, the content of sodium lauryl sulfate in the Aquacoat ECD dispersion has been demonstrated to cause reduced drug release rates in acidic media versus media of neutral pH (65.66). 

In an early study by Lin et al., insulin-loaded polylactic acid (PLA) microcapsules were synthesized by an emulsification-solvent evaporation process originally reported by Beck et al. Several parameters in the synthesis process were modified with the intention of optimizing the insulin release profile. Such modifications included variations in types, concentrations, and viscosities of protective colloids used in the emulsification process. Polyvinyl alcohol (PVA), when used as the protective colloid in the fabrication process, was found to produce the PLA microparticles in reproducible quality. Further studies revealed that the concentration PVA directly affects the PLA particle size and the surface characteristics of the microcapsules. With higher concentrations of PVA, microparticles tended to be smaller and to have a smoother surface. When the release profiles of the microcapsules were stud-... 

CS-based thiolated microgels with an average size of 18 pm have been prepared either by water-in-oil (w/o) emulsification solvent evaporation" or by precipitation-miaonization technique." For thiolation, 2-iminothiolane (Trout s rea nt) was covalently linked to CS via an amidine bond leading to the formation of CS-4-thiobutylamidine. Such polymers show higher mucoadhesive and permeation-enhandng properties than unmodified CS," " which makes them ideal precursors for nasal or oral dmg delivery systems. 

H. Ueda and J. Kreuter, Optimization of the preparation of lop-eramideloaded poly (1-lactide) nanoparticles by high pressure emulsification solvent evaporation. /. MicroencapsuL, 14, 593-605 (1990). 

J. Jaiswal, S. K. Gupta and J. Kreuter, (2004). Preparation of biodegradable cyclosporine nanoparticles by high-pressure emulsification-solvent evaporation process. J. Control Release, 96(1), 169-178. 

STABILIZERS USED TO PREPARE POLYMERIC MICROPARTICLES BY EMULSIFICATION/ SOLVENT EVAPORATION METHOD Aminabhavi T Kulkarni V Kulkami A Karnatak University... 

Details are given of the use of various stabilisers in the preparation of polymer microparticles and the outcome in terms of particle size and encapsulation efficiency. Data are presented for polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymer and polyphosphazene microparticles loaded with drugs and prepared by emulsification/solvent evaporation. 18 refs. 

The most common technique used for the preparation of PLGA nanoparticles is the emulsification-solvent evaporation technique. This technique allows the encapsulation of hydrophobic drugs and consists of dissolving the polymer and the compound in an organic solvent. The emulsion oil (O) in water (W) is prepared by adding water to a polymer solution. The nanosized droplets are induced by sonication or homogenization. The solvent is then evaporated or extracted and the nanoparticles collected after centrifugation [69,70]. 

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