Reports of low levels of the nitrosamine impurity N-Nitrosodimethylamine (NDMA) in some metformin products outside of the US have prompted an investigation into the diabetes drug in the US, according to the Food and Drug Administration (FDA).
In a statement, Janet Woodcock, MD, director of FDA’s Center for Drug Evaluation and Research said that the FDA is aware that some regulatory agencies outside of the US are recalling metformin products, however, at this time, no recalls have been issued in the US. “The FDA is investigating whether metformin in the US market contains NDMA, and whether it is above the acceptable daily intake limit of 96 nanograms,” said Woodcock, adding that the agency would recommend recalls if high levels of nitrosamine impurities were found.
The FDA announcement comes on the heels of a major US recall of ranitidine products following the discovery of NDMA, which is classified as a probable human carcinogen. The recall was extended to another H2-blocker, nizatidine, after testing confirmed that the product contained unacceptable levels of NMDA. To address the issue, the FDA announced that manufacturers of both ranitidine and nizatidine would need to expand their testing to include all lots of the medication before making them available to the public.
NDMA was one of several nitrosamine impurities implicated in the massive recall of angiotensin II receptor blockers (ARBs) as well. Earlier this year, the Agency issued a statement clarifying that the risk of cancer associated with exposure to nitrosamine impurities in ARBS was likely much lower than what was initially estimated. While the risk of cancer may be increased in individuals who are exposed to these genotoxic substances above acceptable levels and for long periods of time, according to the Agency, those who take a drug that contains NDMA at-or-below the acceptable daily intake level are not expected to be at an increased risk, even if the drug is ingested daily for 70 years.
“Our investigations, including our current investigation of metformin, take into account the medical necessity of the drug, how many Americans may take it, and whether there may be alternative treatments available,” said Woodcock. “The American public can expect that we will act quickly to address any issue as soon as we find out about it.”
For more information visit fda.gov.