Patent ID: 8802148

Claim:
A method for the preparation of microparticles containing an active substance embedded in a polymer matrix, comprising the steps of: a) combining a solution of an active substance dissolved in a smaller amount of a first solvent L1 selected from water or organic solvent with a solution of a polymer in a larger amount of a second organic solvent L2, said solvent L2 dissolving the polymer but being a non-solvent for the active substance, thereby effecting precipitation of the active substance in the combined solvent L1 and solvent L2 solution to obtain a suspension of the active substance having an organic phase as a continuous phase, b) mixing the combined solvent L1 and solvent L2 solution with an aqueous surfactant solution wherein L2 is partially soluble in the aqueous surfactant solution and the mixing results in a phase transition from having an organic continuous phase to having an aqueous continuous phase, thereby solidifying the polymer, forming a matrix and embedding the active substance within the polymer to obtain a suspension of microparticles; wherein said active substance is selected from the group of compounds that are sensitive to denaturation, degradation in aqueous solutions or shear forces.