Supercritical fluid spray processes for microencapsulation and formation of submicron aqueous dispersions of pharmaceutical compounds

Precipitation with a Compressed Fluid Antisolvent (PCA) and Rapid Expansion from Supercritical Solution (RESS) are two processes based on supercritical fluids that are capable of producing submicron particles. Novel variations of these basic processes have been examined to produce stable particles of various pharmaceutical compounds. PCA is an antisolvent precipitation technique where an organic solution of drug + polymer in solvent is atomized (sprayed) into supercritical (SC) CO₂. Upon liquid mixing, the solute materials precipitate to form microparticles. A Vapor-over-Liquid technique has been used to produce larger, uniform particle sizes of biodegradable polymers. By suspending a protein in the solvent phase, the protein can be encapsulated/coated by the precipitating polymer. RESS is a process by which a homogeneous solution at supercritical conditions is sprayed through an expansion nozzle to atmospheric conditions. The resultant change in phase leads to the precipitation of the solute materials. The production of extremely small particles (<50 nm) have been predicted but rarely demonstrated. Typically, particle growth occurs to form larger (~1 μm) particles. A novel adaptation was developed, dubbed RESAS (Rapid Expansion from Supercritical to Aqueous Solution), wherein the expansion is conducted within an aqueous environment. The aqueous phase can contain surfactant or lipid stabilizers to capture and preserve submicron particles of water-insoluble drug actives in the form of a suspension.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Chemical Engineering

Grantor

The University of Texas at Austin

Year dc:date.issued

2003

Author dc:creator

• Young, Timothy John

Advisor dc:contributor.advisor

• Johnston, Keith P., 1955-

• Compressed Fluid Antisolvent
• Rapid Expansion from Supercritical Solution
• Supercritical fluids
• Microencapsulation
• Submicron aqueous dispersions
• Pharmaceutical compounds

Statement dc:rights

• Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/2152/29916

OAI identifier oai:identifier

oai:repositories.lib.utexas.edu:2152/29916