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One of our readers recently wrote to us about the article “Metformin: First-Choice Drug for Type 2 Diabetes” in our August issue and expressed concern that we previously had identified metformin (FORTAMET, GLUCOPHAGE, GLUMETZA, RIOMET) as a “Worst” drug but now classify it as a “Best” drug for treating type 2 diabetes. The reader also was troubled by the article’s discussion of the relaxation of restrictions on the use of the drug for certain diabetes patients with kidney disease. I...
One of our readers recently wrote to us about the article “Metformin: First-Choice Drug for Type 2 Diabetes” in our August issue and expressed concern that we previously had identified metformin (FORTAMET, GLUCOPHAGE, GLUMETZA, RIOMET) as a “Worst” drug but now classify it as a “Best” drug for treating type 2 diabetes. The reader also was troubled by the article’s discussion of the relaxation of restrictions on the use of the drug for certain diabetes patients with kidney disease. I thought other readers would benefit from reading my response to these concerns.
After metformin was first approved by the Food and Drug Administration(FDA) in 1995, we did initially designate it as a Do Not Use drug.[1] This initial designation was based in part on the fact that the drug is a biguanide, the same family as phenformin, which was withdrawn from the U.S. market in 1977 because of hundreds of deaths from lactic acidosis, a serious adverse reaction caused by the buildup of lactic acid in the blood. Phenformin is the only drug ever banned by the FDA as an imminent hazard to public health. At the time of its FDA approval, metformin also was known to cause lactic acidosis, although to a much lesser extent than phenformin, but its increased survival benefits had not yet been established.
But as more information about metformin’s risk-benefit profile became available, our assessment of the drug evolved. In 2005, we changed our designation of the drug to Limited Use.[2] This modification was prompted in particular by the results of a large clinical trial conducted in the UK which found that metformin treatment improved survival and reduced cardiovascular complications in overweight subjects with newly diagnosed type 2 diabetes.[3] Therefore, as discussed in our August issue, we now recommend metformin as the best choice for initial drug treatment for type 2 diabetes patients who have tried and failed to control their blood sugar through diet and exercise.
Of note, when metformin was first approved by the FDA, the drug’s product labeling warned against using the drug in any patient with any degree of kidney disease. However, studies subsequently have shown that patients with mild kidney impairment and certain patients with moderate kidney impairment can safely use the drug. Patients with more severe kidney disease should not use metformin because they are at greatest risk of lactic acidosis. For this reason, we continue to designate it as a Limited Use drug.
Thus, our assessments of drugs are not static. Our team of independent experts routinely reviews new research regarding the drugs covered in Worst Pills, Best Pills News. When important new information about the safety or effectiveness of a drug becomes available, we will update our recommendations and designation of the drug accordingly.
References
[1] Wolfe SM, Sasich LD, Hope R. Worst Pills, Best Pills: A Consumer’s Guide to Avoiding Drug-Induced Death or Illness. New York, NY:Simon & Schuster, Inc; 1999:558-559.
[2] Wolfe SM, Sasich LD, Lurie P, et al. Worst Pills, Best Pills: A Consumer’s Guide to Avoiding Drug-Induced Death or Illness. New York, NY:Simon & Schuster, Inc; 2005:421-426.
[3] UK Prospective Diabetes Study (UKPDS) Group. Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes (UKPDS 34). Lancet. 1998;352(9131):854-865.
