To date, seven manufacturers of the top-selling diabetes medication, Metformin, have recalled the drug from store shelves after the cancer-causing-contaminant, NDMA, was discovered in batches.
The latest manufacturer to recall the prescription is Sun Pharma, which late last month, announced a voluntary recall of one lot of its extended-release (ER) metformin hydrochloride oral suspension (Riomet ER). In the release the company stated the recalled lot represents 747 bottles with an expiration date of October 2021.
According to the FDA, the level of NDMA–classified as a probable human carcinogen–has been found to be above the allowable Acceptable Daily Intake (ADI) limit established by the agency.
Although no adverse events have been reported from taking Riomet/Metformin, it’s likely that there will be lawsuits against manufacturers such as Sun Pharma. Thousands of consumers who claim to have developed cancer as a result of taking the heartburn medication, Zantac, have filed lawsuits against ranitidine manufacturers, who make the generic histamine-2 (H2) blockers that reduce stomach acid.
Ranitidine (Zantac is a brand name of a ranitidine drug) remedies were recalled by the FDA in April of this year because of NDMA impurities. The news was alarming, considering that an estimated 15 million Americans were taking ranitidine prescription drugs at the time of the recall. Users of Metformin, one of the most commonly-prescribed drugs in the United States, are even greater. Nearly 80 million prescriptions were written for the drug in 2017. Metformin is nearly always the first drug prescribed for people newly diagnosed with type 2 diabetes. Approximately one-quarter of Metformin prescriptions are for the extended release/Riomet version.
NDMA can form naturally, as is the case with certain food products, including highly-processed lunch meats, or it can form unintentionally in industrial uses, such as drug manufacturing. According to the FDA, the level of impurity increases in tainted drugs over time, and when the packaging or drug itself is stored at higher than room temperature.
The FDA advises those taking any medications to not discontinue doing so without first talking to their prescribing doctor. Additionally, FDA is, to date, unaware of the source of NDMA contamination in Metformin.
Update – November 4, 2020:
Missouri-based Nostrum Laboratories voluntarily recalled two lots of its 750-mg extended-release metformin tablets. The manufacturer did not disclose the exact number of bottles involved in the recall. The lots contain packages of 100 metformin tablets each. Thus far, in addition to Nostrum, Metformin manufacturers that have issued recalls include Granules Pharmaceuticals, Apotex, Amneal, Lupin, Marksans, Teva and Bayshore Pharmaceuticals.