Preparation of microparticles for controlled release of water-soluble substances

摘要

The subject of the present invention is a process for preparing microparticles of the microsphere type of a water-soluble substance and a biocompatible and biodegradable polymer controlling the kinetics of release of the said substance consisting of a matrix of the said polymer within which the said water-soluble substance is regularly dispersed, characterized in that a) the said polymer is dissolved in a first volatile organic solvent immiscible with water, b) the said water-soluble substance is dissolved in a second solvent which is miscible with the said first solvent, is a solvent for the polymer, and miscible with water, c) the solution of the said substance and the solution of the said polymer are mixed, d) an organic phase of the polymer and of the said substance is obtained which is then emulsified in an immiscible dispersant medium consisting of an aqueous phase containing an emulsifying agent, e) the two solvents are then removed from the microspheres being formed with stirring, the first solvent being removed by evaporation, the second solvent and part of the first solvent which is miscible therewith being removed by passage towards the aqueous phase by a mechanism of phase separation, f) after removal of the solvents, the microspheres formed are recovered, optionally after washing in water and sieving.