Process for coating droplets or nanometric particles

A process for coating droplets or solid particles with sizes below 1 micron which contain a chemically or biologically active substance in which the coating is comprised of one or more biocompatible polymers, characterized by;

• preparing a first phase comprising a fine dispersion of droplets or solid particles in a solution of a solvent and a non solvent for the polymer forming the coating and containing a surfactant or suspending agent,
• preparing a second phase which contains the polymer or mixture of polymers dissolved in a solvent or mixture of miscible solvents,
• mixing the two phases continuously in a mixing zone without agitation or ultrasonication while maintaining a constant ratio of the two phases and a constant volume of the two phases in the mixing zone, and
• spraying the resulting mixture into an evaporation system where it is converted into a pulverized form by elimination of the solvent under reduced pressure so that the polymer is deposited around the droplets or particles.