NDMA in Metformin: FDA Finds Low Levels in Only 2 of 10 Tested Products
The US Food and Drug Administration (FDA) on Monday said that no tested samples of the type 2 diabetes drug metformin contained unaccceptable levels of the N-Nitrosodimethylamine (NDMA) impurity. The testing was done because if people are exposed to NDMA above the acceptable levels, it may increase the risk of cancer.“Some metformin drug products tested showed no detectable levels of NDMA, while others showed low levels of NDMA,” FDA said, noting that the low levels are similar to what one would be exposed to from grilled or smoked meats.
The agency also said it has not identified NDMA in metformin active pharmaceutical ingredient.
The only NDMA FDA found was in six lots of Actavis’ Rx Metformin 1000mg ER and Rx Metformin 500mg ER, but the levels were 0.01-0.02 micrograms-mcg/tablet. FDA says that consuming up to the acceptable daily intake limit, 0.096 micrograms, of NDMA per day is considered reasonably safe for human ingestion based on lifetime exposure.
“Patients should continue taking metformin to keep their diabetes under control. It could be dangerous for patients with this serious condition to stop taking their metformin without first talking to their health care professionals,” the agency said. To date, FDA has not recommended metformin recalls in the US.
FDA said it will post the methods used in metformin laboratory testing in the near future. The US agency is collaborating with the European Medicines Agency, Health Canada and the UK’s Medicines and Healthcare products Regulatory Agency on the metformin testing, as Singapore’s Health Sciences Authority in December recalled three out of 46 locally marketed metformin products after determining they contained NDMA “above the internationally acceptable level.”
In contrast to the metformin testing results, FDA said last November that it found NDMA was present in all tested samples of the heartburn drug ranitidine. Ranitidine products from Sandoz, Aurobindo and Dr Reddy's exceeded the acceptable daily intake limit for NDMA, while ranitidine products from Strides Shasun and Watson did not, according to FDA’s analysis.
Laboratory analysis of metformin products