Following a comprehensive literature review, the FDA is requiring labeling changes for metformin-containing medications stating that the drug can be prescribed to patients with mild renal impairment and, in some cases, moderate impairment. Previously, use of metformin in patients with renal dysfunction was not recommended because of the risk of lactic acidosis, a rare but life-threatening condition.
The agency is also recommending that clinicians use estimated glomerular filtration rate (eGFR) to assess kidney function rather than blood creatinine concentration because eGFR takes into account factors such as patient age, gender, race, and/or weight. Clinicians should obtain eGFR at least yearly in patients taking metformin. Those at increased risk for renal impairment, such as the elderly, should be assessed more frequently.
The FDA is requiring manufacturers of metformin-containing medications to update drug labels following a comprehensive review of the medical literature.
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If the eGFR falls below 45 mL/minute/1.73 m2 after starting metformin, clinicians need to reassess the benefits and risks of treatment.
In addition, clinicians should:
- Stop metformin in patients whose eGFR falls below 30 mL/minute/1.73 m2.
- Discontinue metformin before iodinated contrast imaging in patients with an eGFR 30–60 mL/minute/1.73 m2 and in patients with a history of liver disease, alcoholism, or heart failure.
- Reevalute eGFR after the imaging procedure and resume metformin if renal function is stable.
