Fabrication and Characterization of Risperidone Implants As an Extended Antipsychotic Delivery System, Exploring the Role of Excipients Publisher



Saadat E¹ ; Abdollahi A² ; Dorkoosh FA^{1, 3} Show Affiliations
Source: Journal of Pharmaceutical Innovation Published:2015

Abstract

Introduction: Implant is a promising delivery system for chronically used drugs. Excipients play an important role in physicochemical properties and more importantly drug release profile from the implant system; therefore, selecting appropriate materials in matrix formulation is an important issue. Objective: The main purpose of the present study is to explore the role of various excipients on the physicochemical characteristic of risperidone (Ris) implants. In this study, various Ris implant formulations with polyethylene glycol (PEG) as hydrophilic and cholesterol (Chol) as hydrophobic excipients were fabricated and evaluated. Methods: Ris implants were fabricated by casting method. Mathematical modeling was employed to explore the release mechanism of various formulations. In order to analyze the mechanical strength of implants, texture analysis was performed. The physical state of Ris in implants matrix was analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) was used for the morphology investigation of implants. Fourier transform infrared spectroscopy (FTIR) was used to explore any changes in the chemical structure of the drug in formulation. Results: Implant formulations with Chol showed sustained release of Ris as long as 59 days relative to 32 days with PEG. Mathematical evaluation of Ris release showed an erosion-based mechanism for implant formulations with Chol, whereas implants with PEG followed a diffusion release mechanism. Texture analysis of implants showed higher mechanical strength for the formulation with Chol. Both DSC and XRD studies confirmed partial conversion of crystalline Ris to amorphous form in formulations with Chol. The water uptake and matrix bulk erosion of implants showed lower erosion, and the water uptake for formulations with Chol in comparison to formulations with PEG. FTIR analysis showed no changes in the chemical structure of Ris in all formulations. © 2015, Springer Science+Business Media New York.