After a global scare over carcinogen contamination in heartburn med Zantac, regulators are growing increasingly wary about other drugs that may have flown under the radar. Now, generic metformin, a Type 2 diabetes medication, could be next in the FDA’s firing line.
The FDA is testing samples of metformin for the probable carcinogen N-Nitrosodimethylamine (NDMA) that has already been tied to global recalls of generic and branded Zantac earlier this year and for “sartan”-based heart pressure drugs in 2018.
“The agency is in the beginning stages of testing metformin; however, the agency has not confirmed if NDMA in metformin is above the acceptable daily intake (ADI) limit of 96 nanograms in the U.S., FDA spokesman Jeremy Kahn said in an email. “These investigations take time. The FDA will communicate further information when we understand more of the situation and of what, if any, actions health care professionals and patients should take.”
Scrutiny over metformin, a generic drug produced globally, follows the global scare over NDMA contamination in Zantac this summer that led to industrywide recalls. In November, the FDA put out what amounted to a confidence-booster for the drug, saying that the agency’s testing found NDMA amounts comparable to that found in “grilled or smoked meats.”
But the ball could already be rolling on metformin after the Singaporean Health Sciences Authority announced Wednesday it had recalled three of 46 versions of the drug sold in the country after finding NDMA above the “internationally acceptable amount.”
The authority said the risk to patients taking those products was low because those products had been supplied locally for only a short time.
The European Medicines Agency has also said it is testing metformin samples for NDMA and has so far found no unsafe levels of the contaminant, Bloomberg reported.
Whether drugmakers follow their own example on metformin as they did with Zantac––including global distribution halts and recalls––has still yet to be seen. However, the ongoing scrutiny over that drug continues to play out among global regulators.
On Wednesday, the FDA said all producers of Zantac (ranitidine) and nizatidine should test lots of the drugs for NDMA before shipping to consumers. If unacceptable levels of NDMA are found, the results should be reported to the FDA and not put out on the market, the administration said.
“We continue to work with industry and regulatory agencies around the world to determine the reasons for NDMA in these drugs and have developed and posted multiple testing methods to identify NDMA in (Zantac),” the FDA said in a release.
Drugmakers and retailers began pulling lots of generic and brand Zantac off the shelves after online pharmacy Valisure alerted the FDA and the industry to the presence of NDMA in Zantac in September. Valisure also filed a Citizen Petition with the FDA seeking to have the agency pull ranitidine drugs from the market and create viable tests for NDMA in them. NDMA is one of three impurities the FDA discovered last year in sartan blood pressure meds that led to a global recall.
In mid-October, drugmakers including GlaxoSmithKline––the original producer of branded Zantac––Sanofi, Teva, Dr. Reddy’s Laboratories and others opted to pull the drug off the market. Retailers including Wal-Mart, CVS, Walgreens and Rite Aid also decided to clear the drugs off their shelves.
