| 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. This variance is solubility generates pseudo-microparticles which have a number median diameter which is substantially smaller than the size of the administered microparticles. The pseudo-microparticles can be engulfed by antigen presenting cells of the immune system, or absorbed by the Peyer's patches in the gut. |