Recent reports of metformin drug products contaminated with unacceptable levels of the probable human carcinogen N-Nitrosodimethylamine (NDMA) prompted a national sampling of post-market metformin drug products. To most broadly sample the market and minimize supply chain bias, metformin medication samples were crowdsourced directly from individuals across many states in the United States. 128 samples were received, and liquid chromatography-high resolution mass spectrometry tests for a panel of nitrosamines revealed significant levels of NDMA that trend with labeling company. 42% of all medication samples contained detectable levels of NDMA and, when scaled to maximum daily tablet dose, 36% of all medication samples contained NDMA levels exceeding the FDA daily acceptable intake limit. The highest NDMA detection from the tested samples was 1565 ng per tablet, which, when commonly taken four times a day, is 65 times the United States Food and Drug Administration (FDA) acceptable daily intake limit. Results underscore the need for immediate product recalls of tainted medications and an overall investigation of metformin manufacturing practices.
https://www.medrxiv.org/content/10.1101 ... 20110635v1