Preparation of polylactide-polyglycolide microparticles that have a sigmoid release profile

摘要

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.