Carcinogens found in 16 lots of metformin

Online pharmacy Valisure submitted a petition to the FDA on March 2 to recall and investigate several lots of metformin, one of the most widely used diabetes drugs today, Bloomberg reports.

In-house testing by Valisure revealed N-nitrosodimethylamine, or NDMA, in 16 batches of metformin produced by 11 drug companies. Exposure to NDMA in small amounts is inevitable—we ingest it via water and food—but Valisure found that in one batch of metformin manufactured by Amneal Pharmaceuticals LLC, NDMA levels were 16 times the daily acceptable limit of 96 nanograms a day. Other drug companies implicated in the petition include Ascend Laboratories LLC and Actavis Pharma Inc.

Bloomberg reported there have been metformin recalls in Canada this month and in Singapore late last year. Still, there haven’t been any formal recalls in the U.S., despite the fact that the FDA announced in December that it would be testing metformin for carcinogenic impurities.

“It’s unclear why Valisure’s results differ from the FDA findings,” Bloomberg reporter Emma Court wrote in the story. “Valisure said it largely followed the FDA’s protocol for testing for NDMA in metformin, with the exception of changes it said were made to make the method more precise. David Light, Valisure’s founder and chief executive officer, said it’s also possible the FDA got samples that weren’t representative of the general drug supply.”

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