Valisure, the online pharmacy that discovered contaminated Zantac, has petitioned the U.S. Food & Drug Administration (FDA) for a metformin recall, after new round of testing detected high levels of N-Nitrosodimethylamine (NDMA) – a probable human carcinogen – in some samples of the widely used diabetes medication.
The FDA announced in December that it was investigating the possibility that metformin products might be contaminated with NDMA after the drug was recalled in Singapore. The agency later said that while some metformin samples had tested positive for the chemical, the levels detected were well below the acceptable daily intake limit of 96 nanograms.
Yesterday, however, Valisure announced that it had found significantly higher levels of NDMA in 16 of 38 metformin samples it tested, including drugs manufactured Amneal Pharmaceuticals LLC, Ascend Laboratories LLC, and Actavis Pharma Inc. The highest levels were found in Amneal’s metformin, which in some cases contained as much as 16-times the FDA’s recommended daily limits. Several companies’ metformin contained more than 10 times the limit.
Valisure has since petitioned the FDA for a metformin recall and requested that the agency investigate how NDMA came to contaminate the medications.
“Valisure’s results will be of significant concern to medical practitioners who already struggle to prescribe safe medications and who rely on external government and private sector oversight to ensure contaminant-free drugs,” the petition states. “Due to the discovery of significant levels of NDMA contamination, Valisure’s pharmacy will not sell the affected batches of metformin it has acquired and Valisure cannot obtain a refund for these tainted products because they have not been recalled.”
Last Fall, Valisure petitioned the FDA to recall Zantac and generic ranitidine products after an earlier tests also found that the popular heart burn drugs were contaminated with NDMA. The chemical was apparently detected in every sample tested and often at levels that far exceeded the FDA’s daily limits. Valisure also suggested the instability of the ranitidine molecule could result in the production of NDMA once Zantac is subject to conditions created by human digestion.
Last month, Emery Pharma filed a second Zantac recall petition, after its testing suggested ranitidine could produce NDMA when subjected to high temperatures typically encountered during storage and shipment.
The FDA is still investigating contaminated ranitidine and has not ordered an across-the-board Zantac recall. However, various drug makers have opted to pull their prescription and over-the-counter ranitidine products from the market. Generic and name-brand versions of Zantac have also been removed from store shelves at Walmart, Walgreens, Rite-Aid and CVS.
In 2018, the discovery of NDMA in generic angiotensin II receptor blockers (ARBs) led drug makers around the world to recall valsartan, losartan, and irbesartan-containing heart and blood pressure medications.