Soon after massive recalls of high blood pressure medications and heartburn drugs, the FDA is now looking into carcinogenic impurities in the most widely-prescribed diabetes drug in the U.S.
Some regulatory agencies outside the U.S. are recalling some metformin drugs due to low levels of the carcinogenic impurity N-Nitrosodimethylamine (NDMA). There are no metformin (Glucophage, Glumetza) recalls affecting the U.S. currently, says Janet Woodcock, MD, director of FDA’s Center for Drug Evaluation and Research, in a statement.
“The FDA is aware that some metformin diabetes medicines in other countries were reported to have low levels of NDMA. Based on the information we have available, the levels of NDMA seen outside the U.S. are within the range that is naturally occurring in some foods and in water,” Woodcock says.
However, the agency is investigating whether metformin in the U.S. market contains NDMA and if quantities exceed the daily-intake limit of 96 nanograms, according to Woodcock.
“The agency will also work with companies to test samples of metformin sold in the U.S. and will recommend recalls as appropriate if high levels of NDMA are found,” Woodcock says.
Over the past year and a half, several drugs, including angiotensin II receptor blockers (Valsartan, losartan) and ranitidine (Zantac), have been found to contain small amounts of NDMA.
The FDA also announced expanded testing requirements for ranitidine manufacturers.
Type 2 diabetes patients should continue taking metformin to keep their diabetes under control, Woodcock says. “It could be dangerous for patients with this serious condition to stop taking their metformin without first talking to their health care professional. The FDA recommends prescribers continue to use metformin when clinically appropriate, as the FDA investigation is still ongoing, and there are no alternative medications that treat this condition in the same way.”
The FDA is continuing to test and research possible sources for the several drugs found to contain NDMA, Woodcock says. “We are taking a systematic approach to identify medicines with nitrosamines above acceptable daily intake limits and remove them from the market.”