Metformin and Renal Function

Metformin-containing Drugs: Drug Safety Communication - Revised Warnings for Certain Patients With Reduced Kidney Function

AUDIENCE: Pharmacy, Nephrology, Internal Medicine, Patient

ISSUE: FDA is requiring labeling changes regarding the recommendations for metformin-containing medicines for diabetes to expand metformin’s use in certain patients with reduced kidney function. The current labeling strongly recommends against use of metformin in some patients whose kidneys do not work normally. FDA was asked to review numerous medical studies regarding the safety of metformin use in patients with mild to moderate impairment in kidney function, and to change the measure of kidney function in the metformin drug labeling that is used to determine whether a patient can receive metformin.

FDA concluded, from the review of studies published in the medical literature, that metformin can be used safely in patients with mild impairment in kidney function and in some patients with moderate impairment in kidney function. FDA is requiring changes to the metformin labeling to reflect this new information and provide specific recommendations on the drug’s use in patients with mild to moderate kidney impairment.

FDA is also requiring manufacturers to revise the labeling to recommend that the measure of kidney function used to determine whether a patient can receive metformin be changed from one based on a single laboratory parameter (blood creatinine concentration) to one that provides a better estimate of renal function (i.e., 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. See the FDA Drug Safety Communication for additional information, including a data summary and a list of metformin-containing drugs.