ABSTARCT surface and completely covered with a coating of


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 prepare sustained release matrix granules of Metformin
hydrochloride which are further coated to extend the release of drug over a longer
time period.

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Metformin hydrochloride granules were prepared by mixing all the dry
powders in a V – cone blender and wetting the powder mix 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. These were marked as CMG3 and CMG4 which were later filled into
empty capsules. The granules were evaluated for micromeretic properties and
characterized for percentage yield, particle size distribution, percent drug
content and in vitro release of the

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 revealed 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 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 elimination half-life and fluctuations 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.