Could metformin, the popular drug used to treat type 2 diabetes, cause cancer? According to the Food and Drug Administration, the frightening answer might be “yes,” thanks to an impurity in the drug known as N-Nitrosodimethylamine, or NDMA.
At the end of May, the FDA began calling on pharmaceutical companies to voluntarily recall contaminated batches of metformin, particularly the extended-release version. By June 8, four companies had agreed to recall the drug, with more expected to follow.
What exactly is NDMA, and how did it end up in a diabetes drug?
“NDMA is a common contaminant found in water and foods, including cured and grilled meats, dairy products, and vegetables. Everyone is exposed to some level of NDMA. The FDA and the international scientific community do not expect it to cause harm when ingested at low levels,” the FDA said in a press release.
However, extended-release metformin produced by several different drug companies contained levels of NDMA above the safety threshold. The impurity went undetected until an online pharmacy called Valisure tested several batches of metformin. According to Valisure, they tested 38 batches of the drug produced by 22 different companies, and almost half—16 batches made by 11 different companies—were contaminated.
Valisure’s test results prompted a Citizen Petition urging the FDA to issue recalls of metformin. The petition was filed with the FDA on March 2nd. It took the FDA almost three months to request “voluntary” recalls, meaning companies are still legally permitted to sell batches of metformin containing high levels of NDMA.
Of course, the link between metformin and cancer is not a straight line. In the U.S., NDMA is classified as a “probable” human carcinogen rather than a “known” human carcinogen. As the American Cancer Society says, “Carcinogens do not cause cancer at all times, under all circumstances.” Factors like individual genetics, age, length of exposure, and the method of exposure all influence whether someone will develop cancer after being exposed to a known or probable human carcinogen.
However, the FDA acknowledges that elevated levels of NDMA ingested over long period of time is unsafe. That means a person taking metformin for years or decades to control diabetes could indeed be at higher risk of developing cancer.
“Nitrosamine impurities may increase the risk of cancer if people are exposed to them at above-acceptable levels over long periods of time,” the FDA said. “We are working to ensure medicines on the U.S. market do not exceed the acceptable intake limit.”
Diabetic patients who have been prescribed metformin should not quit taking their medication without a doctor’s supervision. However, they should pay close attention to the recalls and know which companies are producing their medication. Discussing concerns about a medication with a physician is always the safest route.
The attorneys at Tittle & Perlmuter are monitoring the metformin recalls and are ready to take action against pharmaceutical companies that negligently allowed contaminated drugs to reach the market. If you or a loved one developed cancer after taking metformin, contact us for a free consultation.