Guar Gum-Based Floating Microspheres of Repaglinide Using 32 Factorial Design: Fabrication, Optimization, Characterization, and In Vivo Buoyancy Behavior in Albino Rats.

In this present study, floating microspheres of repaglinide were successfully fabricated by the solvent evaporation technique with varying ratios of guar gum, hydroxypropyl methylcellulose, and ethylcellulose with polyvinyl alcohol. Microspheres were characterized by production yield, particle size, in vitro buoyancy, entrapment efficiency, in vitro drug release, and in vivo floating behavior in albino rats. The formulation process was optimized for stirring speed (X1) and concentration of polymer ratio (X2) on dependent variables such as percentage entrapment efficiency, percentage yield, in vitro buoyancy, and percentage of drug release by the 32 factorial Design-Expert® 12, trial version, software. The optimized formulation was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy and was successfully formulated with the highest percentage of cumulative drug release (94.26 ± 3.10), entrapment efficiency (74.70% ± 2.16%), and particle size (50.34 ± 3.67 μm) and remains buoyant for 24 h in simulated gastric fluid (0.1N HCL) with high in vitro buoyancy percent (84.90 ± 2.88). When the drug-polymer solution of dichloromethane and ethanol is dropped in polyvinyl alcohol solution, it leads to the formation of a shell and produces cavities, creating the buoyant nature of floating microspheres. X-ray imaging indicates the uniform distribution and buoyant nature of microspheres in the gastric fluid for a 10-h period.