ABSTRACT:
The aim of present study was to formulate the oral controlled release metformin hydrochloride matrix tablets by using locust bean gum as rate controlling polymer and to evaluate drug release parameters as per various release kinetic models. The tablets were prepared by wet granulation method. Granules were prepared and evaluated for loose bulk density, tapped density, compressibility index and angle of repose, shows satisfactory results. All the granules were lubricated and compressed using 12.8 mm flat faced punches. Compressed tablets were evaluated for uniformity of weight, content of active ingredient, friability, hardness, in vitro release studies swelling and eroding behavior. All the formulations showed compliance with Pharmacopoeial standards. The in vitro dissolution study was carried out for 12 hours using paddle (USP type II) method in phosphate buffer (pH 6.8) as dissolution media. The prepared matrix tablets were shown 98.89%, 98.18%, 96.32%, 94.52%, 91.36% and 88.45% release over a period of 12 hours. Formulations F-1 and F-2 failed to sustain release beyond 8 hours and 10 hours, respectively. Among all the formulations, F-1 gave the release profile close to the marketed sample of metformin hydrochloride (M-SR), but slow and well controlled drug release was obtained from formulation F-4. The kinetic values obtained from different plots of formulation F-4 was close to the marketed sample of metformin hydrochloride (M-SR). The Selected formulation (F-4) was subjected to stability studies for 3 months, which showed stability with respect to release pattern. The drug release follows first order kinetics and the mechanism was found to be diffusion coupled with erosion. The FT-IR study did not show any possibility of metformin hydrochloride / locust bean gum interaction with the formulation excipients used in the study.