Many metformin users have been on edge lately waiting for the U.S. Food and Drug Administration to finish testing the drug to determine whether it might contain unsafe levels of NDMA. Now the results are in.
NDMA, also known as N-Nitrosodimethylamine, is a naturally occurring substance that is often found in trace amounts in medications as well as in water and other natural sources. In small amounts, it is not harmful. However, the substance can also be created as a byproduct of industrial processes, and if it surpasses certain levels, it may be capable of causing cancer.
Recently, high levels of NDMA have been found in several medications, including common blood pressure medications and heartburn medications, leading them to be recalled. Rumor had it that metformin might be the next drug to be recalled in the U.S. for NDMA contamination. The drug was recalled in certain areas of the world, such as Singapore, and the FDA launched an investigation into whether metformin sold in the U.S. might contain unsafe concentrations of NDMA.
However, the metformin products the FDA tested have not been found to contain much NDMA, if any at all. Only two out of 10 drug products tested contained any detectable amount of NDMA; the rest were free and clear of the substance as far as researchers can tell. The research was performed in collaboration with the European Medicines Agency, Health Canada, and the UK’s Medicines and Healthcare products Regulatory Agency.
“Some metformin drug products tested showed no detectable levels of NDMA, while others showed low levels of NDMA,” says the FDA.
Low levels refer to amounts of the substance that are not dangerous and are likely about the same amount of NDMA you might receive from consuming grilled or smoked meats.
Of all 16 lots of metformin tested, NDMA was only found in six lots of Actavis’s Rx Metformin 1000 mg extended-release and Rx Metformin 500 mg extended-release tablets. The NDMA in these drugs was only about 0.01 to 0.02 micrograms-mcg per tablet, and the FDA deems anything below 0.096 micrograms safe for human consumption based on lifetime exposure numbers, meaning a person who consumes this amount of NDMA daily for 70 years is not expected to have an increased risk of cancer. The amount of NDMA in these drugs, therefore, is less than one-quarter of the acceptable amount.
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Additionally, the FDA did not find any NDMA in the active pharmaceutical ingredient contained in prescription metformin drugs. The agency is expected to post the methods it used in laboratory testing of metformin in the near future for public review.
Based on these findings, the FDA has not recommended a recall of metformin and does not recommend that any patient taking it discontinue use without consulting a physician. “Patients should continue taking metformin to keep their diabetes under control,” the FDA states. “It could be dangerous for patients with this serious condition to stop taking their metformin without first talking to their health care professionals.”
Elizabeth Nelson is a wordsmith, an alumna of Aquinas College in Grand Rapids, a four-leaf-clover finder, and a grammar connoisseur. She has lived in west Michigan since age four but loves to travel to new (and old) places. In her free time, she. . . wait, what’s free time?