Objectives: Metformin
hydrochloride is a potent, biguanide antihyperglycemic agent generally recommended
as a first line drug for the treatment of diabetes mellitus (type II). The
purpose of the present work is to formulate and characterize sustained release coated
matrix granules of Metformin hydrochloride.

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Methods: Metformin
hydrochloride granules were prepared using ethyl cellulose as release retardant
by mixing the powder blend in a V – cone blender and wetting it with aqueous
solution of HPMC K100. The prepared granules (MG1-MG5) were investigated for drug
release data. The granules which an exhibited extended release up to 4hrs were
coated in a standard coating pan with blends of Eudragit RS and RL to further
enhance release period and marked as CMG3 and CMG4 which were later filled into
empty capsules. The granules were evaluated for micromeretic properties and
characterized for percentage yield, percent drug content, particle size
distribution and in vitro release of
the drug.

Results: All
the formulations showed percentage yield in the range of 77.66 to 82.86% and
drug content in the range of 78.23 to 96.62%. CMG3 showed drug release of
97.02% for 12 hrs. FTIR and DSC studies indicated that no possible interaction
existed between the drug and the polymers used. SEM images showed that the
granules were spherical in shape with smooth surface and completely covered
with a coating of polymer. Kinetic analysis of drug release confirmed that drug
release followed zero order kinetics where it is independent of the

Conclusion: From
the results it was analyzed that design of coated granules employing the
polymers used in the present work can produce a sustained release of the drug
over a period of 12hrs.







Keywords:  metformin, sustained
release, V- cone blender, Eudragit, standard coating pan






design of sustained release dosage forms is to slowly release the drug over an extended
time period. They possess a major advantage of improved patient compliance as
the dosing frequency is once or twice daily.1 In case of dosage forms for extended release, multiple unit
forms are mostly preferred over single unit dosage forms as they contain minute
amount of the drug and thus have lower risk of dose dumping.2

Metformin hydrochloride is a potent anti-diabetic
drug with a major drawback of shorter elimination half-life (6.2 hrs.). It acts
in the presence of insulin to enhance glucose use and decrease production of glucose
their by counteracting insulin resistance. The effect of metformin includes enhanced
glucose uptake and its and reduced hepatic gluconeogenesis. Drugs with shorter
biological half-life are suitable candidates for formulation in sustained release
dosage forms. 3-4

The aim of the current investigation is to formulate
coated granules of Metformin hydrochloride. In order to overcome the drawback
of shorter biological half-life and fluctuation in plasma level concentration of
the drug, an attempt was made to sustain the release of the drug by formulating
it as coated granules using retardant polymers.