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

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    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

    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.

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    Charles Patrick Davis, MD, PhD

    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.

Type 2 Diabetes Warning Signs

What brand names are available for metformin?

Glucophage, Glucophage XR, Glumetza, Fortamet, Riomet

Is metformin available as a generic drug?

GENERIC AVAILABLE: Yes

Do I need a prescription for metformin?

Yes

What are the uses for metformin?

  • 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.

What are the side effects of metformin?

The most common side effects with metformin are

These symptoms occur in one out of every three patients. These side effects may be severe enough to cause therapy to be discontinued in one out of every 20 patients. These side effects are related to the dose of the medication and may decrease if the dose is reduced.

Metformin may also cause:

A serious but rare side effect of metformin is lactic acidosis. Lactic acidosis occurs in one out of every 30,000 patients and is fatal in 50% of cases. The symptoms of lactic acidosis are

  • weakness,
  • trouble breathing,
  • abnormal heartbeats,
  • unusual muscle pain,
  • stomach discomfort,
  • light-headedness, and
  • feeling cold.

Patients at risk for lactic acidosis include those with reduced function of the

Quick GuideDiabetes Diet: Healthy Meal Plans for Diabetes-Friendly Eating

Diabetes Diet: Healthy Meal Plans for Diabetes-Friendly Eating

What is the dosage for metformin?

  • 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.
  • Metformin-containing drugs may be safely used in patients with mild to moderate renal impairment. Renal function should be assessed before starting treatment and at least yearly.
  • Metformin should not be used by patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m2  and starting metformin in patients with an eGFR between 30-45 mL/minute/1.73 m2 is not recommended.
  • Metformin should be stopped at the time of or before administering iodinated contrast in patients with an eGFR between 30 and 60 mL/minute/1.73 m2; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Kidney function should be evaluated 48 hours after receiving contrast and metformin may be restarted if kidney function is stable.

Which drugs or supplements interact with metformin?

  • 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.
  • Ioversol (Optiray) and other iodinated 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.
  • Thiazide diuretics, steroids, estrogens, and oral contraceptives may increase blood glucose and reduce the effect of metformin. When these drugs are stopped, patients should be closely observed for signs of low blood glucose.
  • Alcohol consumption increases the effect of metformin on lactate production, increasing the risk of lactic acidosis.

Is metformin safe to take if I'm pregnant or breastfeeding?

  • There are no adequate studies in pregnant women. Most experts agree that insulin is the best treatment for pregnant women with diabetes.
  • Metformin is excreted into breast milk and can therefore be transferred to the nursing infant. Nursing mothers should not use metformin.

What else should I know about metformin?

What preparations of metformin are available?

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

How should I keep metformin stored?

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

Reference: FDA Prescribing Information

Quick GuideDiabetes Diet: Healthy Meal Plans for Diabetes-Friendly Eating

Diabetes Diet: Healthy Meal Plans for Diabetes-Friendly Eating

Summary

Metformin (Glucophage, Glucophage XR, Glumetza, Fortamet, Riomet) is a medication prescribed to treat type 2 diabetes and the prevention of type 2 diabetes in patients who are at risk for type 2 diabetes. Side effects of metformin include:

Drug interactions, dosage, and pregnancy and breastfeeding safety information should be reviewed prior to taking this medication.

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See more info: metformin on RxList
Reviewed on 9/9/2016
References
Reference: FDA Prescribing Information

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