3-month parenteral PLGA microsphere formulations of risperidone: Fabrication, characterization and...

The study aims at formulation and characterization of three months parenteral risperidone loaded polymeric microspheres (p-RLPMs) as a sustained delivery system and established their in vitro and in vivo assessments. The p-RLPMs formulations were prepared by solvent extraction and diffusion method. The optimized p-RLPMs (batch R_PLGA-1) formulation demonstrated favorable different physicochemical properties such as mean particle size (104±5.34μm), percent porosity (44.56±3.11%) and percent drug loading (38.42±2.67%). The physical state characterization, Fourier transformed infrared spectroscopy analysis showed no changes in the chemical structure of risperidone (RPD) in the batch R_PLGA-1 formulation and differential scanning calorimetry study confirmed, pure RPD retained its crystallinity in the batch R_PLGA-1 formulation. The SEM micrographs of the all p-RLPMs formulations revealed the irregular shapes and indentations. The GC/MS results showed that the residual organic solvent content in the batch R_PLGA-1 formulation was below the limits. Pharmacokinetic parameters revealed that optimized R_PLGA-1 formulation exhibited an initial burst followed by an excellent sustained release as compared to pure RPD as well as other formulations. Furthermore, in vivo studies of the batch, R_PLGA-1 formulation showed an antipsychotic effect that was significantly prolonged over that of pure RPD solution for up to 72h with fewer extrapyramidal side effects. Thus, results of this study prove the suitability of using poly(lactic-co-glycolic acid) copolymer to develop sustained release p-RLPMs formulations that can tailor in vivo behavior and enhance the pharmacological effectiveness of the RPD.