There are several extended-release lots of the type-2 diabetes medication, Metformin, that contain high levels of N-Nitrosodimethylamine (NDMA), a cancer-causing chemical, according to the Food and Drug Administration (FDA). They are asking several drug manufacturers to recall the medication voluntarily.

The agency found these high levels primarily in the extended-release formulation of the medication, which is the reason behind the recalls.


About Metformin

In the United States, Metformin is considered to be one of the most widely prescribed medications. For new diabetes patients, this drug is often one of the first oral medications prescribed. In 2017, over 78 million prescriptions for the medication were written, according to the Agency for Healthcare Research and Quality. One-quarter of these prescriptions were extended-release versions of the medication.

Why NDMA Is Harmful

Classified as a known human carcinogen, NDMA can potentially cause cancer. According to studies that were conducted on animals, NDMA can cause kidney, lung, or liver problems in high doses. The medication can also lead to colorectal or gastric cancer, according to the World Health Organization (WHO).

The acceptable daily intake limit for NDMA is 96ng according to the FDA, even though everyone is exposed to some level of it. In 2018, the FDA set this level when they discovered NDMA in some cardiovascular medications.

Pharmaceutical Companies That Have Recalled Metformin

Apotex Corp and Amneal Pharmaceuticals, two drug manufacturers, have recalled 750-milligram and 500-milligram Metformin extended-release tablets since the FDA’s announcement. Before batches of Metformin are distributed, the FDA is asking manufacturers to test them.

Several other companies currently facing scrutiny include:

  • Marksans Pharma Ltd.
  • Lupin Pharma
  • Actavis Pharma Inc.

Pharmaceutical companies are working with the FDA to determine whether there would be a shortage in the United States due to the recommended recalls of this medication. The recalls do not affect Metformin’s immediate-release formula. The FDA stated that the Metformin ER formulation is supplied to a significant portion of the market in the U.S. through additional manufacturers. Due to this, the products are not being recalled at this time.

The NDMA contamination found in Metformin has also been found in the blood pressure medication Valsartan and the heartburn medication Zantac.

Further Recommendations From the FDA

Healthcare providers are being advised by the FDA to only prescribe Metformin when clinically necessary. Additionally, the agency is asking patients to continue taking the medication, even after recalls occur until they are able to contact their provider to request a different treatment option or a replacement prescription.

Manufacturers of ER products containing Metformin are evaluating the risk of excessive NDMA in their medications and testing every batch prior to releasing it into the American market. If the tests indicate that NDMA levels are above the intake level that is considered acceptable by the FDA, the manufacturer is being asked not to release the batch and to contact the agency immediately.

The recall doesn’t apply to Metformin’s immediate-release medications. The FDA advises patients who are currently taking the extended-release tablets should not stop taking the medication abruptly.

Other firms that currently manufacture Metformin extended-release formulas haven’t had their products recalled, according to the FDA. They are determining whether other recall announcements will create shortages and will work with the drug manufacturers to reduce or prevent any shortage of the medication.

Low Levels of NDMA Found in Metformin Formulas in December 2019

NDMA contamination in Metformin isn’t new. A previous announcement was made in December 2019 regarding low levels of NDMA that were found in certain Metformin medications in other countries. The agency followed up this discovery with its own investigation. It was later announced that lab results had discovered small amounts of NDMA in Metformin medications that were sold in the United States in February 2020. The agency did not recommend recalling Metformin at the time because the samples did not exceed the acceptable daily limit of 96ng.

An independent testing laboratory, Valisure, disputed the findings from the FDA in March 2020, citing that they had found unacceptable levels of NDMA contamination in over 42% of the batches they inspected. Valisure asked the FDA in a Public Citizen petition to recall the contaminated products they identified. They feared the situation would only continue to worsen, as supply chains are being ravaged by the current COVID-19 crisis.

Valisure tested 38 batches of Metformin medication from 22 drug companies. The NDMA contained in the medications exceeded the FDA’s acceptable daily limit of 96ng in 16 batches from 11 companies. There were several other batches that contained extremely high levels of NDMA that were 10 times above the acceptable daily intake limit.

From batch-to-batch even within a single company, Valisure also found significant variability, which emphasizes the need for increased testing of some medications at the batch level as indicated in their petition. Emery Pharma, another testing laboratory, was asked to check Valisure’s findings. They came to the same conclusions as Valisure.  

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