FDA Issues Nitrosamine Impurity Alert for Certain Metformin Products

By Adam Hochron

The FDA has issued an alert about certain extended-release metformin prescriptions having higher levels of the nitrosamine impurity N-Nitrosodimethylamine (NDMA) than the agency deems acceptable. 

Following the detection of higher levels of the impurity, the FDA reached out to five firms making the drugs and encouraged them to voluntarily recall their products, according to a press release from the agency. 

“The FDA has strict standards for safety, effectiveness, and quality, and the agency makes every effort based on science and data to help keep the US drug supply safe,” said Patrizia Cavazzoni, MD, acting director of the FDA’s Center for Drug Evaluation and Research. “We understand that patients may have concerns about possible impurities in their medicines and want to assure the public that we have been looking closely at this problem over many months in order to provide patients and health care professionals with clear and accurate answers.” 

The release from the FDA noted that while they have been in contact with some manufacturers of extended release metformin products there are others that are not subject to a potential recall at this time. The release adds that patients currently taking metformin should continue to take their medication until they consult with their doctors who could prescribe a replacement treatment. 

The FDA has identified 96 nanograms per day as an acceptable intake limit for NDMA. Higher levels of Nitrosamine impurities, “may increase the risk of cancer if people are exposed to them at above-acceptable levels over longer periods of time,” according to the release. The FDA also noted that it “does not anticipate that shorter-term exposure levels above the acceptable intake limit would lead to an increase in the risk of cancer.” 

The release said it is encouraging all companies who make an extended release metformin product to “evaluate the risk of excessive NDMA in their product and to test each batch before it is released into the US market.” The list of medications in question can be found on the FDA website.  

Late last year, the FDA announced it was aware of the issue in some metformin products in other countries, according to the release, which started the review of domestically available products. By February of this year, the agency had detected “very low levels of NDMA in some samples, but at that time, no FDA-tested sample of metformin exceeded the acceptable intake limit for NDMA.” 

“Now that we have identified some metformin products that do not meet our standards, we’re taking action,” Cavazzoni said. “As we have been doing this since the impurity was first identified, we will communicate as new scientific information becomes available and will take further action, if appropriate.”


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