Dr. Janet Woodcock
This follows reports of low-level NDMA contamination of metformin in other countries and of a few regulatory agencies issuing recalls for the drug, according to a statement from Janet Woodcock, MD, director of the FDA’s Center for Drug Evaluation and Research.
“There are no metformin recalls affecting the U.S. market at this time,” the agency emphasized in the statement. It said NDMA levels in affected medication have been low, at or even below the acceptable intake limit, and there is currently no evidence indicating that metformin drugs within the United States or European Union have been contaminated.
The FDA advised that patients should continue taking metformin alone or in combination with other drugs to control their diabetes and that it would be dangerous for them to stop taking the medication without first discussing it with their providers. It also recommended that providers continue to use metformin when “clinically appropriate” while the investigation is underway as there are no alternative therapies to treat the disease in the same way.
NDMA is a common contaminant that is found in water and some foods and has probable carcinogenic effects when exposure is too high. The acceptable daily intake for NDMA in the United States is 96 ng/day, according to the statement, though people who take in that amount or less every day for 70 years are not expected to have an increased risk of cancer.
Both the FDA and its counterpart, the European Medicines Agency, have recently investigated the presence of NDMA impurities in ranitidine, a drug used to reduce production of stomach acid, which led to several manufacturers issuing recalls for it.
The agencies have also investigated angiotensin II receptor blockers, which are used to treat hypertension, heart failure, and high blood pressure.
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The presence of NDMA “can be related to the drug’s manufacturing process or its chemical structure or even the conditions in which they are stored or packaged. As food and drugs are processed in the body, nitrosamines, including NDMA, can be formed,” Dr. Woodcock noted in the statement.
“We are monitoring this issue closely to assess any potential impact on patients with diabetes,” said Robert W. Lash, MD, chief professional and clinical affairs officer of the Endocrine Society. “We have members around the world and are concerned about the possibility of carcinogenic impurities in medications, both in the United States and elsewhere.”