The PLGA Microspheres Synthesized by a Thermosensitive Hydrogel Emulsifier for Sustained Release of Risperidone

Abstract

Risperidone is an important antipsychotic agent used for treatment of both acute and chronic schizophrenia. The drug has been effective in resolving the disease’s signs while keeping extrapyramidal side effects as low as possible. To achieve a sustained and gradual release of risperidone from PLGA microspheres, we utilized an emulsifying agent; PLGA-PEG-PLGA triblock (M-triblock), instead of PVA (M-PVA), applying ring-opening polymerization of the triblock via supercritical carbon dioxide (scCO2). PVA and PLGA-PEG-PLGA (as emulsifiers) were successfully employed to prepare risperidone-loaded PLGA microspheres. The scCO2 and microwave irradiation methods were used to construct PLGA-PEG-PLGA copolymers. The microspheres were subjected to various analyses to determine the particles’ sizes, morphological characteristics, and structure (via XRD) and in vitro drug release kinetics. Drug loading capacity and encapsulation percentage were also determined. The results showed a mean diameter of 43.34 ± 2.30 µm for M-PVA, and that of the M-triblock was 57.49 ± 1.21 µm. Risperidone encapsulation percentages were 72.8 ± 2.09 for M-PVAs and 73.4 ± 2.41 for the M-triblock. Particle size, risperidone distribution, and drug loading and encapsulation percentages were similar between M-PVAs and the M-triblock. In scanning electron microscopy (SEM), the morphology of the triblock emulsifier was more uniform than PVAs. The triblock emulsifier showed slower initial drug release than PVAs due to the precipitation of the triblock hydrogel around PLGA microspheres. Overall, the triblock used here can be a good alternative to PVA.