En español | If you take metformin to help manage diabetes, take note: Despite recent warnings and partial recalls by the Food and Drug Administration (FDA), the American Diabetes Association says you should continue taking the drug, which is among the 10 most commonly prescribed in the U.S.
How can that be? “The operative phrase here is ‘partial recalls,’“ explains endocrinologist Emily Nosova, M.D., assistant professor of endocrinology and diabetes at the Mount Sinai Health System, in New York City. “It's challenging to make an overarching recommendation to stop taking a medication that so many people derive benefit from, and take on a daily basis, when we don't have an accurate sense of the number of batches affected by the recall.” As Nosova explains, the generic metformin ER (the extended-release version of the drug) is produced by numerous manufacturers. The FDA partial recall applies to only some batches, leaving “undeniably a great proportion of unaffected batches.”
Of the dozens of companies that manufacture the drug — which controls blood sugar and has long been the first-line treatment for people with type 2 diabetes — most of them are international. The FDA's initial warning about possible contamination centered on just select batches of metformin ER produced in other countries; months later, some U.S. manufacturers were also included. By November, nine manufacturers had issued recalls.
The FDA's warning focused specifically on levels of the carcinogen N-nitrosodimethylamine (NDMA). But medical experts say the levels flagged are within the range of naturally occurring NDMA levels found in water and some foods. On the whole, health care providers have reassured their patients that they can still take the drug.
FDA testing has not found NDMA in batches of conventional immediate-release metformin, the more commonly prescribed version of the drug.
"The concern is not specific to metformin and any known links of the medication to cancer but, rather, the production process utilized by certain manufacturers, as identified on the FDA list,” Nosova explains. “Other medications — for example, blood pressure medications and antacids — have been subject to similar partial recalls."
If you take metformin ER, go to the FDA's Recalls, Market Withdrawals & Safety Alerts site and type “metformin” into the search bar to find out if your brand is among those affected. Or you can ask your pharmacist if your brand was included in the recall. If so, “it's the pharmacist's responsibility to take back the medication and dispense another one,” says Nathan Painter, a clinical professor at the University of California, San Diego Skaggs School of Pharmacy and Pharmaceutical Sciences. “There are extended-release metformin products out there that aren't affected by the recall. If there's no alternative, call your doctor to talk about alternatives that your physician might have to prescribe.”