Abstract: The present invention relates to a sustained release composition for the targeted delivery of biologically active agents to specific tissues and cells. The composition comprises microparticles containing a biocompatible polymer, a water-soluble polymer and a biologically active agent. In one embodiment, the biologically active agent is an antigen or an immunomodulator. In another embodiment, the biologically is a labile agent. The microparticles have a number median diameter of greater than 20 microns upon administration. The water-soluble polymer is present in the sustained released composition in at least about 20% of the dry weight of the microparticle. the sustained release composition provides for the dissolution of the water-soluble polymer of the composition upon hydration, at a much greater rate than the degradation of the biocompatible polymer.

Abstract: Microparticles that include a bisphosphonate and a polymer are produced by a method that includes forming a water-in-oil emulsion by mixing an aqueous solution of the bisphosphonate with a combination of a biocompatible polymer and a polymer solvent. At least one aqueous liquid can be mixed with the water-in-oil emulsion to form a water-in-oil-in-water emulsion and to extract the polymer solvent from the polymer, thereby forming the microparticles. Methods of treating a patient in need of therapy include administering the microparticles described to the patient. In one embodiment, the microparticles are formulated for the sustained release of the bisphosphonate.