The U.S. Food and Drug Administration recently tested the oral diabetes medicine metformin for the presence of N-Nitrosodimethylamine (NDMA), a potent carcinogen, and in February, it published its results. Those tests showed that NDMA was either not detectable or only found at acceptably low levels. 

But online pharmacy Valisure has conducted its own tests on 38 batches, and said that in 16 of them, it found NDMA levels above the 96 nanograms that the FDA deems an acceptable daily intake. In some batches, Valisure found NDMA in quantities more than 10 times that limit. 

Of the 22 companies in total whose metformin drugs it tested, Valisure found batches from 11 that were over the threshold, among them Amneal Pharmaceuticals (AMRX -0.55%). That healthcare company is coming off a disappointing year in which its revenue fell 2% compared to 2018. Its net loss of $362 million was also more than twice its 2018 loss of $170 million. 

Prescription medication.

Image source: Getty Images.

Tests uncover inconsistencies and future problems

To further complicate the results, Valisure said that there was "significant variability" not just from one batch to the next, but even within individual companies' results. CEO David Light says that the COVID-19 outbreak threatens to compound these quality control problems, especially with the potential for a decline in drug manufacturing output from China: "Many of these existing safety and quality issues, like the ones we identified in metformin, likely stem from overseas manufacturers cutting corners. It is certainly possible that many more corners may be cut in the scramble to ramp up production and fill backorders." 

Metformin is the most commonly prescribed drug used by people with type-2 diabetes to help control their blood glucose levels. In Canada, certain brands of metformin drugs were recalled last month because their NDMA levels were too high, but the FDA does not plan to follow Canada's lead.