ABSTRACT:
Of the various attempts to prolong the gastric residence time, use of mucoadhesive polymers is the most sought after. The main objective was to prolong the residence of metformin hydrochloride formulation in upper gastrointestinal tract. Herein we report a method for the preparation of mucoadhesive drug delivery system for metformin hydrochloride, a water soluble drug, using HPMC K4M, Carbopol 934P and Carbopol 971P as mucoadhesive and release controlling polymers. The selection of mucoadhesive polymer was done on the basis of water uptake, shear stress measurement and detachment force. The formulations were prepared by tablet compression method and were evaluated for water uptake, mucoadhesion, differential scanning calorimetry, in vitro and in vivo release. The water sorption studies of the formulation indicated a curvilinear relation for the drug: polymer ratio. The in vitro release studies revealed that the optimum combination of HPMC K4M and Carbopol 971P in the formulation leads to sustained release with a lower burst. The non invasive technique of gamma scintigraphy was explored which confirmed the exact position of the formulation within the gastrointestinal tract. Hence, it is concluded that the mucoadhesive formulation of metformin hydrochloride using mucoadhesive and release controlling polymers could sustain the drug release and remain in upper gastrointestinal tract so that the drug would be available in the dissolved form at the main site of its absorption.