Cardiometabolic Risk

FDA: Metformin Safe for Some Patients with Renal Impairment

The FDA now requires labeling changes to reflect that metformin is safe for use in patients with mild renal impairment and in some patients with moderate renal impairment.

The change updates previous labels warning of use in patients with elevated creatinine levels and the risk of developing lactic acidosis.

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The FDA is also requiring changing the measure used to determine a patients’ eligibility for metformin treatment from blood creatinine concentration to glomerular filtration rate estimating equation (eGFR). “This is because in addition to blood creatinine concentration, the glomerular filtration rate takes into account additional parameters that are important, such as the patient’s age, gender, race and/or weight.”

After reviewing of the medical literature, the FDA made the following recommendations:

  • Obtain the patients eGFR before starting metformin.
  • Metformin is contraindicated with patients with an eGFR below 30 mL/minute/1.73 m2.
  • It is not recommended to begin metformin treatment in patients with eGFR between 30-45 mL/minute/1.73 m2.
  • eGFR should be obtained annually in all patients taking metformin, and more frequently in those who are at higher risk for developing renal failure.
  • Assess the benefits and risks of continued metformin treatment in patients whose eGFR falls below 45 mL/minute/1.73 m2.
  • Discontinue metformin in patients about to undergo iodinated contrast imaging, patients with liver disease, alcoholism, or heart failure, and those who will be administered intra-arterial iodinated contrast.

—Michael Potts

FDA. Metformin-containing drugs: drug safety communication - revised warnings for certain patients with reduced kidney function. Accessed April 11, 2016.