Washington, D.C.—Pharmacists should not expect any recalls of metformin, the most commonly prescribed type 2 diabetes drug in the United States.

The FDA posted laboratory results in early February showing N-Nitrosodimethylamine (NDMA) levels in some metformin products approved in this country, according to a press release.

The agency said it has determined that the levels of NDMA in metformin products tested range from low to undetectable. In fact, as of this point, no sample of metformin tested by the FDA exceeds the acceptable daily intake for NDMA.

The FDA will continue to monitor NDMA in metformin, along with other drugs products, and will provide timely updates of new developments, including product recalls, according to the document.

The FDA has had ongoing investigations related to the presence of nitrosamines, genotoxic impurities, in some types of drugs, according to a statement late last year from Janet Woodcock, MD, director of FDA’s Center for Drug Evaluation and Research.

She pointed out, “Over the past year and a half, several drug products including angiotensin II receptor blockers (ARBs) and ranitidine, commonly known as Zantac, have been found to contain small amounts of nitrosamines such as NDMA. During this time, there has been an ongoing investigation into the presence of nitrosamines in other drug products. This effort is focused on ensuring the drugs used by Americans continue to meet strict quality standards.”

Dr. Woodcock said at the time that U.S. drug regulators were aware that metformin samples in other countries were reported to have low levels of NDMA, explaining, “Based on the information we have available, the levels of NDMA seen outside the U.S. are within the range that is naturally occurring in some foods and in water. While we are aware that some regulatory agencies outside the U.S. may be recalling some metformin drugs, there are no metformin recalls affecting the U.S. market at this time. The FDA is investigating whether metformin in the U.S. market contains NDMA, and whether it is above the acceptable daily intake limit of 96 nanograms.”

She said the FDA would also work with companies to test samples of metformin sold in the U.S. and initiate recalls as necessary if high levels of NDMA are found.

Nitrosamine impurities can increase the risk of cancer in those exposed to them above acceptable levels and over long periods of time. On the other hand, FDA background information notes that someone taking a drug that contains nitrosamines at or below the acceptable daily intake limits every day for 70 years is not expected to have an increased risk of cancer. 

Public health officials explain that nitrosamines also are common in water and foods, including cured and grilled meats, dairy products, and vegetables.

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