Patent ID: 7901606

Claim:
A method of forming porous particles, the method comprising: providing an aqueous suspension of composite particles, the composite particles comprising at least a first material that is not soluble in supercritical carbon dioxide and a second material that is soluble in supercritical carbon dioxide, wherein the first material is a solid selected from the group consisting of pharmaceuticals, biodegradable polymers, biological agents and combinations of two or more thereof, and the second material is a solid selected from the group consisting of lipids, waxes, polymers, sugar acetates and fluorocarbons; and bubbling supercritical carbon dioxide through the aqueous suspension of composite particles to extract the second material from the composite particles and thus form an aqueous suspension of porous particles comprising the first material suspended in water, the porous particles have an aerodynamic size range of from about 0.5 to about 5 microns and a geometric volume diameter of from about 1 to about 20 microns.