The FDA ( Food and Drug Administration ) has required 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 drug labeling strongly recommends against metformin use in some patients whose kidneys do not work normally because use of Metformin in these patients can increase the risk of developing a serious and potentially deadly condition called lactic acidosis, in which too much lactic acid builds up in the blood.
FDA has 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 has required 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 has also recommended 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 kidney function in patients with kidney disease ( i.e., glomerular filtration rate estimating equation [ eGFR ] ).
Metformin-containing medicines are available by prescription only and are used along with diet and exercise to treat type 2 diabetes.
Metformin is available as a single-ingredient product and also in combination with other medicines used to treat diabetes.
Metformin helps control blood sugar in a number of ways. These include helping the body respond better to the insulin it makes naturally, decreasing the amount of sugar the liver makes, and decreasing the amount of sugar the intestines absorb from food.
Common side effects of Metformin include diarrhea, nausea, and upset stomach. Although rare, use of metformin can cause low blood sugar if patients do not eat enough, if they drink alcohol, or if they take other medicines to lower blood sugar.
Approximately 14.4 million unique patients received a dispensed prescription for Metformin or Metformin-containing combination products from U.S. outpatient retail pharmacies in 2014.
FDA has recommended 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 ). 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.
The labeling recommendations on how and when kidney function is measured in patients receiving Metformin will include the following information:
• Before starting Metformin, obtain the patient’s eGFR;
• Metformin is contraindicated in patients with an eGFR below 30 mL/minute/1.73 m2;
• Starting Metformin in patients with an eGFR between 30-45 mL/minute/1.73 m 2 is not recommended;
• Obtain an eGFR at least annually in all patients taking Metformin. In patients at increased risk for the development of renal impairment such as the elderly, renal function should be assessed more frequently;
• In patients taking Metformin whose eGFR later falls below 45 mL/minute/1.73 m 2, assess the benefits and risks of continuing treatment. Discontinue Metformin if the patient’s eGFR later falls below 30 mL/minute/1.73 m2 ;
• Discontinue Metformin at the time of or before an iodinated contrast imaging procedure 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. Reevaluate eGFR 48 hours after the imaging procedure; restart Metformin if renal function is stable. ( Xagena )
Source: FDA, 2016