Elevated levels of the probable human carcinogen NDMA have been detected in several lots of extended-release formulations of metformin, the first-line treatment for type 2 diabetes, the Food and Drug Administration (FDA) said in a press announcement. The agency said it has recommended five drug companies issue recalls of their products.

The agency said it is working closely with manufacturers to ensure their metformin products are being tested and is assessing whether metformin ER recalls will result in shortages for consumers.

NDMA, short for N-nitrosodimethylamine, is a known environmental contaminant found in water and foods. The FDA considers consuming up to 96 nanograms of NDMA per day reasonably safe for human ingestion based on lifetime exposure. But sustained higher levels of exposure to the impurity may increase the risk of cancer in humans, the agency said.

On April 1, the FDA called for the withdrawal of all heartburn and acid reflux medications containing ranitidine, including Zantac, after finding that levels of NDMA in Zantac could exceed the agency’s daily limit during normal storage and handling.

The FDA had previously investigated NDMA in blood pressure and heart failure medicines called angiotensin II receptor blockers (ARBs), which it later determined was due to substandard manufacturing practices. The findings resulted in numerous recalls.

Late last year, the FDA announced it had become aware of NDMA in some metformin products sold in other countries. The agency began testing metformin in the U.S. supply and, by February 2020, had identified “very low levels” in some samples. No recalls were issued. But a private laboratory challenged the FDA, filing a citizen petition, which prompted the FDA to conduct further tests.

“FDA laboratories tested the same metformin lots that the private laboratory found to contain NDMA above the acceptable intake limit. The agency confirmed unacceptable NDMA levels in some, but not all, of those lots. In other instances, our laboratory detected NDMA in lots that the private laboratory did not,” the FDA said in the news release. “The agency also found that the levels of NDMA, when present, were generally lower than reported by the private laboratory. Given FDA scientists’ deep experience quantifying these impurities in drugs, the agency is confident in the reliability of the FDA’s testing method and results and will continue to take action based on the latest scientific information. The results have also been consistent with the findings of other regulatory agencies’ laboratories around the world.”

The FDA is recommending patients continue taking metformin tablets even after recalls occur, until they consult with their health care professional who can prescribe a replacement. “Patients with type 2 diabetes could face dangerous health risks if they stop taking their prescribed metformin.

Beasley Allen attorney Frank Woodson is actively investigating potential claims involving regular Zantac/ranitidine use that may have led to cancer of the stomach, colon, intestines, kidneys, or pancreas. If you or a loved one may have been affected, please contact us. Beasley Allen is not currently taking claims related to metformin.

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