Drug Comparisons

Biguanides are used to treat Type 2 diabetes. They work by: (1) decreasing the absorption of sugar or "glucose" by the intestines, (2) decreasing the production of glucose in the liver, and by (3) increasing the body's ability to use insulin more effectively. Metformin is currently the only drug in this category, but it is available in 2 formulations: a regular-release formulation (e.g., Glucophage, Riomet) and an extended-release formulation (e.g., Fortamet, Glucophage XR, Glumetza). Riomet is the only liquid form of metformin available.

Drugs in this Class
Metformin Tablets (Glucophage Tablets)
Metformin Extended-Release Tablets (Fortamet Extended-Release Tablets, Glucophage XR Tablets, Glumetza Extended-Release Tablets)

Summarizing the Evidence

• According to the American Diabetes Association's Standards of Care for the treatment of diabetes, metformin is considered a first-line therapy for adults with Type 2 Diabetes. It is particularly useful in patients who may be overweight or obese because it does not typically cause weight gain like other oral anti-diabetic medications.

• A few studies have shown that metformin can even be effective at preventing or delaying the onset of diabetes in patients who are at risk for developing diabetes. However, diet and lifestyle modifications (such as exercise and low sugar and low carbohydrate diet) proved to be more effective at preventing diabetes.

• Recent reviews of case reports, other studies, and national databases indicate that metformin may also be safer than what was originally thought. Specifically, the risk for lactic acidosis?a serious condition caused by too much lactic acid in the body and associated with deep and rapid breathing, vomiting, and abdominal pain?may occur less frequently with metformin than traditionally thought by healthcare providers.

• Metformin is the active ingredient in both formulations of Glucophage. However, Glucophage XR tablets are made with a special release mechanism that releases the metformin active ingredient into the body over a longer period of time (approximately 24 hours), compared to regular-release Glucophage. This 24-hour release mechanism allows Glucophage XR to be dosed once daily, and it can be helpful for patients who have difficulty remembering to take medications more than one time per day. Regular-release Glucophage is usually dosed 2 to 3 times daily.

• Since Glucophage and Glucophage XR contain the same active ingredient (metformin) and only differ in the way the active ingredient is released in the body, these two products are equally effective in lowering blood sugar levels.

• Regular-release and extended-release Glucophage are available generically. Generic Glucophage products (called by the active ingredient name, metformin) contain the exact same active ingredient and work in the same manner as brand name Glucophage; however, generic formulations are less expensive. There currently is no generically available liquid metformin product.

• If you have difficulty remembering to take multiple daily doses of metformin then extended-release metformin may be helpful since it only has to be taken once daily. However, extended-release products are generally more expensive. If you do not have difficulty remembering to take your medication doses, generic formulations of regular-release metformin would be an equally effective and less expensive treatment option. Of course, the product and/or formulation to use should be decided by your physician and may depend on your personal preference and prescription benefits formulary.

Dosing and Administration

• Regular-release metformin is typically taken 2 to 3 times daily. Extended-release metformin can be taken once daily.

Generic Availability

• Regular-release Glucophage (generic name: metformin) is available generically. Glucophage XR is also available generically (generic name: extended-release metformin). Regular-release liquid metformin is not available generically.

Drug Interactions

Some interactions between medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how the drugs interact and the severity of the interaction, please use our Drug Interactions Checker.

Side Effects

To view specific side effect information, please use our Side Effect Checker.

Additional Information

References

1. America Diabetes Association Clinical Practice Recommendations 2007. Standards of Medical Care. Diabetes Care 2007. 30(suppl 1): 4-41.

2. Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002; 346(6):393-403.

3. Diabetes Prevention Program Research Group. The influence of age on the effects of lifestyle modification and metformin in prevention of diabetes. J Gerontol A Biol Sci Med Sci. 2006;61(10):1075-81.

4. Glucophage XR [package insert]. Princeton, NJ. Bristol-Myers Squibb Company. July 2002.

5. Glucophage [package insert]. Princeton, NJ. Bristol-Myers Squibb Company. July 2002.

6. McEvoy GE, ed. American Hospital Formulary Service drug information 2002. Bethesda, MD: American Society of Health-System Pharmacists; 2002:2997-3018.

7. Drugdex Database. In: Gelman CJ, Rumack BH, editors. Denver: Micromedex Inc. 2006.

8. Tahrani, A; GI Varughese, J H Scarpello FWF Hanna: Metformin, heart failure, and lactic acidosis: is metformin absolutely contraindicated? BMJ 2007;335:508-512.

9. Eurich D; et al: Benefits and harms of antidiabetic agents in patient with diabetes and heart failure: systematic review. BMJ 2007;335:497.

Last Updated: April 2008
This content was created by members of the DrugDigest team of experts and is solely under DrugDigest's editorial control.

Note: The above information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist, or other healthcare professional. It should not be construed to indicate that the use of the product is safe, appropriate, or effective for you. Consult your healthcare professional before taking any medication.