Design, Development and Characterization of Liquid Oral Sustained Release in situ Gel Formulation of Glimepiride

Background: In situ gel is a type of floating polymeric formulation that is in solution form before administration, but undergoes gelation in situ to form a gel upon contact with physiological fluids. Objective: The objective of present study was to design and evaluate sustained release in situ gel suspension of Glimepiride (GLP) and compare it with marketed formulation. Method: Different formulations of GLP were prepared using different concentration of gelling agents, like sodium alginate and calcium carbonate. Polysorbate 80 was used as wetting agent and sodium citrate was included to prevent gelation outside the gastric environment. Optimization was done using ‘32’ randomized full factorial designs. The formulation was evaluated for different parameters including rheological parameter, Particle size, sedimentation rate, in vitro gelling ability, in vitro drug release study and floating ability. Pharmacokinetic study was conducted on Wistar rats for testing of bioequivalance. A single blind study was performed for taste test in human volunteers. Result: The suspension demonstrated a pseudo-plastic behavior with instant gelation. The in situ gelling suspension showed drug release of 99.85% in 12 h. Formulations were floating for more than 12 h. Conclusion: Thus, sustained release floating drug delivery system (FDDS) of in situ gelling suspension of GLP was formulated having sustained drug action for 12 h. Inferences drawn from in vitro and preliminary in vivo studies suggest that in situ gel is a potential delivery system for GLP for improving bioavailability in comparison with marketed formulation.