Abstract: Particles having a tap density less than about 0.4 g/cm3 are formed by spray drying from a colloidal solution including a carboxylic acid or salt thereof, a phospholipid, a divalent salt and a solvent such as an aqueous-organic solvent. The colloidal solution can also include a therapeutic, prophylactic or diagnostic agent. Preferred carboxylic acids include at least two carboxyl groups. Preferred phospholipids include phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerols, phophstidylserines, phosphatidylinositols and combinations thereof. The particles are suitable for pulmonary delivery.

Abstract: Improved porous particles for drug delivery to the pulmonary system, and methods for their synthesis and administration are provided. In a preferred embodiment, the porous particles are made of a biodegradable material and have a mass density less than 0.4 g/cm3/. The particles may be formed of biodegradable materials such as biodegradable polymers. For example, the particles may be formed of a functionalized polyester graft copolymer consisting of a linear a-hydroxy-acid polyester backbone having at least one amino acid group incorporated therein and at least one poly(amino acid) side chain extending from an amino acid group in the polyester backbone. In one embodiment, porous particles having a relatively large mean diameter, for example greater than 5 &mgr;m, can be used for enhanced delivery of a therapeutic agent to the alveolar region of the lung.