Daily Health Headlines

metformin, Glucophage, Glucophage XR, Glumetza, Fortamet, Riomet

Medical and Pharmacy Editor:

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

DRUG CLASS AND MECHANISM: Metformin is an oral medication that lowers blood glucose (sugar) by influencing the body's sensitivity to insulin and is used for treating type 2 diabetes. Insulin is a hormone produced by the pancreas that controls glucose levels in blood by reducing the amount of glucose made by the liver and by increasing the removal of glucose from the blood by muscle and fat tissues. As a result, insulin causes blood glucose levels fall. Diabetes caused by a decrease in production of insulin that causes increased production of glucose by the liver, and reduced uptake (and effects) of insulin on fat and muscle tissues. Metformin acts by increasing the sensitivity of liver, muscle, fat, and other tissues to the uptake and effects of insulin. These actions lower the level of sugar in the blood.

Unlike glucose-lowering drugs of the sulfonylurea class, for example glyburide (Micronase; DiaBeta) or glipizide (Glucotrol), metformin does not increase the concentration of insulin in the blood and, therefore, does not cause excessively low blood glucose levels (hypoglycemia) when used alone. In scientific studies, metformin reduced the complications of diabetes such as heart disease, blindness and kidney disease. Metformin was approved by the FDA in December 1994.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 500, 850, and 1000 mg. Tablets (extended release): 500, 750, and 1000 mg. Solution: 100 mg/ ml

STORAGE: Metformin should be stored at room temperature between 20 C  to 25 C (68  F to 77 F).

PRESCRIBED FOR: Metformin is used for treating type 2 diabetes in adults and children. It may be used alone or in combination with other diabetic medications. Metformin also has been used to prevent the development of diabetes in people at risk for diabetes, treatment of polycystic ovaries, and weight gain due to medications used for treating psychoses.

DOSING: For treating type 2 diabetes in adults, metformin (immediate release) usually is begun at a dose of 500 mg twice a day or 850 mg once daily. The dose is gradually increased by 500 mg weekly or 850 mg every two weeks as tolerated and based on the response of the levels of glucose in the blood. The maximum daily dose is 2550 mg given in three divided doses.

If extended tablets are used, the starting dose is 500 mg or 1000 mg daily with the evening meal. The dose can be increased by 500 mg weekly up to a maximum dose of 2000 mg except for Fortamet (2500 mg of Fortamet, once daily or in two divided doses). Glumetza tablets (500 -1000mg formulations are given once daily (either 1000 to 2000mg). Fortamet and Glumetza are modified release formulations of metformin. Metformin should be taken with meals.

For pediatric patients 10-16 years of age, the starting dose is 500 mg twice a day. The dose can be increased by 500 mg weekly up to a maximum dose of 2000 mg in divided doses.

Children older than 17 years of age may receive 500 mg of extended release tablets daily up to a maximum dose of 2000 mg daily. Extended release tablets are not approved for children younger than 17 years of age.

DRUG INTERACTIONS: Cimetidine (Tagamet), by decreasing the elimination of metformin from the body, can increase the amount of metformin in the blood by 40%. This may increase the frequency of side effects from metformin.

Contrast media may reduce kidney function which reduces elimination of metformin, leading to increased concentrations of metformin in the blood. Metformin should be stopped 48 hours before and after use of contrast media.

Medically Reviewed by a Doctor on 7/8/2014

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Need help identifying pills and medications?Use the pill identifier tool on RxList.

Pharmacy Author:

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

Medical and Pharmacy Editor:

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

Tweet