FORMULATION, IN-VITRO RELEASE KINETICS AND STABILITY INTERPRETATION OF SUSTAINED RELEASE TABLETS OF METFORMIN HYDROCHLORIDE

Objective: The objective of the present study was to formulate, study the in-vitro release kinetics and stability of sustained release tablets of metformin hydrochloride.Methods: Sustained release formulations that would maintain the plasma level for 8 – 12 h might be sufficient for daily dosing of metformin. The granules of metformin hydrochloride were prepared by wet granulation method using polymers such as ethyl cellulose (EC) and hydroxyl propyl methyl cellulose E15 (HPMC E15).Results: The granules were evaluated by determining the angle of repose (26.010±0.110 to 31.950±0.100), bulk density, tapped density, Hausner ratio and Carr's index. It shows satisfactory results. The tablets were subjected to measurement of thickness (4.78 ± 0.07 to 5.20±0.13 mm), weight variation (within limit), drug content (98.08±0.20 to 99.22±0.22%), hardness (9.27±0.16 to10.30±0.97 kg/cm2), friability (0.2to 0.3%w/w), and in-vitro release studies.Conclusion: It was found that as the concentration of HPMC increased the drug release rate declined due to formation of viscous layer. The release can be fine tuned by adding a hydrophobic polymer like EC in the hydrophilic matrix of HPMC. The release mechanisms were analyzed and were found that the release data was best fitted with Higuchi equation although there is no significant difference between the correlation coefficients of Zero-order and Higuchi model. The result also shows different parameters of stability studies and compare with initial results of different batches.Â