Poly (D, L-lactide) nanosuspensions of risperidone for parenteral delivery: formulation and in-vitro evaluation

Risperidone, an "atypical" antipsychotic drug, having large scope for prolonged psychotic treatments through novel parenteral drug delivery systems. Polymeric nanoparticles suspensions containing risperidone made of poly (D, L-Lactide) were designed by nanoprecipitation method using polymeric stabilizer (Pluronic F-68 or Pluronic F-127). The prepared nanosuspensions were characterized for particle size by photon correlation spectroscopy and scanning electron microscopy. The free dissolved drug in the nanosuspension was determined by bulk equilibrium reverse dialysis bag technique. In vitro release studies were carried out using dialysis bag diffusion technique. The particle size of the prepared nanoparticles in the nanosuspensions ranged between 78-184 nm. Nanoparticles of risperidone in the nanosuspensions were obtained with high encapsulation efficiency (91-94 %). The drug release from the risperidone nanosuspension was sustained in some batches for more than 24 h with 75% drug release whereas release from risperidone solution showed release within 1.5 h. The release pattern of drug is analyzed and found to follow first order equation and Fickian diffusion kinetics. These studies suggest the feasibility of formulating risperidone loaded poly (D, L-Lactide) nanoparticles suspension for the treatment of psychotic disorders.