Formulations
Metformin is sold under several trade names, including Glucophage XR, Carbophage SR, Riomet, Fortamet, Glumetza, Obimet, Gluformin, Dianben, Diabex, and Diaformin.
Metformin IR (immediate release) is available in 500 mg, 850 mg, and 1000 mg tablets; all are now generic in the US.
Metformin SR (slow release) or XR (extended release) was introduced in 2004, in 500 mg and 750 mg strengths, mainly to counteract the most common gastrointestinal side effects, as well as to increase compliance by reducing pill burden. No difference in effectiveness exists between the two preparations.
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