Metformin recalled again over cancer risk: Key details to know

An existing recall of popular diabetes medication metformin has been expanded over the presence of an impurity that may increase cancer risk. The expanded recall comes from Marksans Pharma Ltd. and covers the brand name Time-Cap Labs. Two different strengths of the drug have been recalled, but the company notes that patients shouldn't immediately stop taking the recalled medication.

The latest recall notice covers a huge number of metformin HCL extended-release tablets with expiration dates ranging from October 2020 to April 2022. The products were sold in bottles with between 90 and 1,000 tablets in 500mg and 750mg strengths. The FDA provides a list of all of the newly recalled metformin products, including their UPC codes and other identifying details.

The reason for the expanded recall is one we've heard before — the tablets may have excessively high levels of an impurity called N-Nitrosodimethylamine (NDMA), which has been identified as a potential carcinogen in humans. The recall covers a total of 76 unexpired lots of the drug, building upon the initial recall announced in early June.

Because NDMA is found in water and food, it is impossible to entirely avoid it; however, its classification as a probable carcinogen means there's a limit on how much can be present in one's daily medication, with that limit currently sitting at 96ng per day. A number of past medication recalls have been initiated over potentially high levels of this impurity.

As with previous metformin recalls, patients currently taking one of these recalled products are warned to continue taking the drugs while waiting for their doctor or pharmacist to provide a replacement — the risk of uncontrolled blood sugar is greater than the risk of possible exposure to the probable carcinogen. Customers are advised to return the recalled medication to the store from which it was purchased.