The invention concerns a method for coating powdery solid active substancescharacterized in that it comprises the following steps: a) providing (2; 3; 4)a mixture comprising at least one coating agent wherein is dissolved a supercriticalor subcritical fluid in conditions of temperature and pressure enabling saidfluid to be maintained in supercritical or subcritical conditions; b) providing(7) individualized moving particles of at least one powdery solid active substance;c) contacting (8) the mixture and the moving individualized particles of activesubstance in conditions of temperature and pressure ensuring simultaneouslyexpansion of the supercritical or subcritical fluid and its restoration to gaseousstate, the atomization of the coating agent and its solidification around themoving individualized particles of active substance; d) separating and recuperatingthe coated particles (9). The invention also concerns coated microparticlesof active substance, each microparticle comprising su ccessively a core containingthe active substance and a shell containing the coating agent, characterizedin that they are obtainable by the inventive method and in that the active substanceis solid and heat-sensitive at room temperature, and in that the average sizeof the active substance core is less than 50 m.
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