Transmucosal Delivery of Metformin- A Comprehensive Study

Discovered in the 1920s, the biguanide metformin hydrochloride is still the first line drug in the management of Type 2 diabetes mellitus. Metformin hydrochloride is absorbed slowly and incompletely from the gastrointestinal tract. The present research work was undertaken with the aim of developing a fast dissolving film of metformin hydrochloride, suitable for oral trans mucosal administration. Fast dissolving films allow rapid drug dissolution in the oral cavity, ensuring bypass of first pass metabolism resulting in rapid absorption. Films of metformin were prepared by solvent casting method using Hydroxypropyl methylcellulose K15 (HPMC). Six formulations (F1-F6) of metformin hydrochloride were prepared and evaluated for their physical characteristics such as tackiness, thickness, tensile strength, elongation, weight variation, folding endurance, drug content and surface pH. The compatibility of the drug with HPMC was confirmed by FTIR studies. The formulations were subjected to disintegration, in-vitro drug release and the optimised formulation was evaluated for pharmacodynamic studies in diabetic rats. Among the formulations (F1-F6) F4 was found to be the best formulation which contained Hydroxypropyl methyl cellulose K15 at weight ratios of 1:4 and showed excellent film forming characteristics such as disintegration time at 42 sec and percentage drug release of 94.2% within 5 minutes. Pharmacodynamic assessment in diabetes induced rats demonstrated that the fast dissolving films of metformin had a quicker onset of action compared to conventional formulation.