Glucophage XR

[Metformin]

Drug Description
DESCRIPTION

GLUCOPHAGE ® (metformin hydrochloride tablets) and GLUCOPHAGE ® XR (metformin hydrochlo-ride extended-release tablets) are oral antihyperglycemic drugs used in the management of type 2 diabetes. Metformin hydrochloride (N, N-dimethylimidodicarbonimidic diamide hydrochloride) is not chemically or pharmacologically related to any other classes of oral antihyperglycemic agents.

Metformin hydrochloride is a white to off-white crystalline compound with a molecular formula of C 4 H 11 N 5 °HCl and a molecular weight of 165.63. Metformin hydrochloride is freely soluble in water and is practically insoluble in acetone, ether, and chloroform. The pKa of metformin is 12.4. The pH of a 1% aqueous solution of metformin hydrochloride is 6.68.

GLUCOPHAGE tablets contain 500 mg, 850 mg, or 1000 mg of metformin hydrochloride. Each tablet contains the inactive ingredients povidone and magnesium stearate. In addition, the coating for the 500-mg and 850-mg tablets contains hydroxypropyl methylcellulose (hypromellose) and the coating for the 1000-mg contains hydroxypropyl methylcellulose and polyethylene glycol.

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GLUCOPHAGE XR contains 500 mg of metformin hydrochloride as the active ingredient. Each tablet contains the inactive ingredients sodium carboxymethyl cellulose, hydroxypropyl methylcel-lulose, microcrystalline cellulose, and magnesium stearate.

System Components and Performance GLUCOPHAGE XR tablets comprise a dual hydrophilic polymer matrix system. Metformin hydrochloride is combined with a drug release controlling polymer to form an "inner" phase, which is then incorporated as discrete particles into an "external" phase of a second polymer. After administration, fluid from the gastrointestinal (GI) tract enters the tablet, causing the polymers to hydrate and swell. Drug is released slowly from the dosage form by a process of diffusion through the gel matrix that is essen-tially independent of pH. The hydrated polymer system is not rigid and is expected to be broken up by normal peristalsis in the GI tract. The biologically inert components of the tablet may occasionally remain intact during GI transit and will be eliminated in the feces as a soft, hydrated mass.