Design and Characterization of Hallow Porous Floating Microspheres of Favipiravir

Abstract

The present investigation deals with the design and characterization of favipiravir floating microspheres for gastro retentive drug delivery system by employing 3² factorial design and also to investigate the main effects of different independent variables on microspheres that float. The emulsion solvent diffusion method was used to manufacture floating microspheres with Eudragit S 100 as the polymer. These microspheres will extend the release of the medicine, reducing the frequency of administration and the harmful effects caused by fluctuations in plasma concentration with conventional dosage forms. The main effect of independent variables like polymer Eudragit S 100 concentrations (50, 100, 150 mg) and stirring time (1, 2 and 3 hours) on the performance of microspheres. Formulated microspheres were characterized for responses including drug release, particle size, and entrapment efficiency and floating time. Based on the results of the responses, the optimized composition was arrived using the response surface method graphical and numerical optimization method using design of experiments (DoE) software. Then, the optimized formulation (OFES) was prepared and evaluated for the four responses compared with predicted values to find the validity of the selected model. The optimized formulation was further analyzed for drug-excipient compatibility by fourier-transform infrared (FTIR), differential scanning calorimetry (DSC), and also analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) analysis. Further zeta potential and micrometric properties were also observed. The results for the formulation FES 1 to 9 found were, that particles size ranged from 0.192 to 0.277 μm, entrapment efficiency ranged from 68.65 ± 1.9 to 76.25 ± 3.2%, percentage drug release range was from 89.25 ± 0.24 to 93.68 ± 0 .25%, and floating time range was from 12 to 23 hours. As per the design, OFES an optimized formulation fitted with the concentration of Eudragit S 100 of 139.1 mg and stirring time of 1-hour. Regarding the kinetic release, the responses were best fitted with Higuchi model of R² value of 0.9795 with kinetic mechanism of non-fickian diffusion with R² value of 0.9499, indicating good linearity. The combination of different variables and their effects on responses were investigated well using factorial design, and an optimized formulation was developed for favipiravir.