A process for preparing biodegradable polyparticles of poly (D, L-lactide-co-glycolide) polymer (PLGA) having a sigmoid release profile of risperidone, contained in the microparticles, comprising the following steps: a. preparing an internal oil phase by dissolving the PLGA polymer and risperidone in an organic solvent, in which the concentration of polymer in the internal oil phase is in the range of 5-8% w / w； b. preparing an external aqueous phase consisting of water, polyvinyl alcohol (PVA), optionally an aqueous buffer solution to adjust the pH to a value at which risperidone has the lowest solubility, and the same organic solvent used in the oil phase； wherein the amount of organic solvent added to the external phase is sufficient to saturate the external phase； C. emulsify the internal phase in the external phase either by mechanical agitation or by using a high shear homogenizer； d. transfer the emulsion into an extinguishing medium that has the temperature set at 5 ° C and thermostatically controlled； and. separate the resulting hardened microparticles and optionally wash the microparticles； and f. Dry the microparticles in a single drying stage, without any subsequent washing and / or drying stage.Un procedimiento de preparación de micropartículas biodegradables de polímero de poli(D,L lactida-co-glicolida) (PLGA) que tienen un perfil de liberación sigmoideo de risperidona, contenida en las micropartículas, que comprende las siguiente etapas: a. preparar una fase oleosa interna disolviendo el polímero de PLGA y la risperidona en un disolvente orgánico, en la que la concentración de polímero en la fase oleosa interna está en el intervalo de 5-8% p/p； b. preparar una fase acuosa externa que consiste en agua, alcohol polivinílico (PVA), opcionalmente una disolución tampón acuosa para ajustar el pH a un valor en el que la risperidona presenta la menor solubilidad, y el mismo disolvente orgánico usado en la fase oleosa； en la que la cantidad de disolvente orgá
