Guar Gum-Based Floating Microspheres of Repaglinide Using 3 2 Factorial Design: Fabrication, Optimization, Characterization, and In Vivo Buoyancy Behavior in Albino Rats Amit Kumar Patel, 1 Manoj Kumar Mishra, 1 Jitendra Gupta, 2 Saurav Ghoshal, 1 Reena Gupta, 2 and Krishna Kushwaha 3 1 Department of Pharmaceutics, Shambhunath Institute of Pharmacy, Jhalwa, Prayagraj, Uttar Pradesh, India. 2 Institute of Pharmaceutical Research, GLA University, Mathura, Uttar Pradesh, India. 3 Department of Pharmacy, Ashoka Institute of Technology and Management, Varanasi, Uttar Pradesh, India. ABSTRACT 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 (X 1 ) and concentration of polymer ratio (X 2 ) on dependent variables such as percentage entrapment efficiency, percentage yield, in vitro buoyancy, and percentage of drug re- lease by the 3 2 factorial Design-Expert Ò 12, trial version, soft- ware. The optimized formulation was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, dif- ferential 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 mm) and re- mains buoyant for 24 h in simulated gastric fluid (0.1N HCL) with high in vitro buoyancy percent (84.90 – 2.88). When the Color images are available online. DOI: 10.1089/adt.2020.1006 ª MARY ANN LIEBERT, INC.  VOL. 19 NO. 2  FEBRUARY/MARCH 2021 ASSAY and Drug Development Technologies 63 Downloaded by Mary Ann Liebert, Inc., publishers from www.liebertpub.com at 04/12/21. For personal use only. FOR REVIEW ONLY NOT INTENDED FOR DISTRIBUTION OR REPRODUCTION