Riomet ER Metformin Recall Issued Over Cancer-Causing NDMA in Diabetes Drug

Riomet ER, an extended release version of the generic diabetes drug metformin, contains high levels of the cancer-causing chemical byproduct N-Nitrosodimethylamine (NDMA), resulting in a recall announcement on Wednesday.

The Riomet ER recall was issued on September 23, affecting one lot of the extended release oral suspension drug, after it was determined the drug contains levels of NDMA above the allowable Acceptable Daily Intake limit established by the FDA.

NDMA is considered a human carcinogen, which can be a byproduct of the drug manufacturing process or from inherent processes associated with certain pharmaceutical ingredients.

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In recent years, detection of the chemical has resulted in widespread Zantac recalls and valsartan recalls, and users of the popular heartburn and blood pressure medications have reported developing various types of cancer following long-term use, including breast cancer, bladder cancer, stomach cancer, testicular cancer and other injuries.

This latest recall affects one lot of Riomet ER (metformin hydrochloride for extended-release oral suspension) 500 mg per 5 mL, with lot number AB06381, NDC Number 10631-019-17 and an expiration date of 10/2021.

The recalled generic metformin pills were included in an estimated 747 cartons. Each carton contains a bottle of drug pellets, a bottle of diluent and a dosing cup. They were distributed nationwide by Sun Pharmaceutical Industries, Inc., also known as Sun Pharma.

Metformin NDMA Problems

In December 2019, reports first warned about the potential risk of metformin NDMA contamination problems, after some versions of the drug sold outside the United States tested positive for the chemical, raising concerns that metformin recalls may be necessary. However, the FDA indicated at the time that testing of products distributed in the U.S. found that the NDMA levels in metformin were undetectable or below federal limits for exposure to the chemical.

In March 2020, the independent online pharmacy Valisure filed a citizen’s petition urging the FDA to recall metformin, after independent testing found levels of NDMA in certain pills was higher than the agency’s recommended daily exposure threshold of 96 nanograms.

Since then, the FDA says it has confirmed some of the Valisure findings, resulting in a number of separate recalls as specific lots of the medication have been found to contain higher than acceptable levels of NDMA.

Since the metformin recalls began, a number of consumers have filed NDMA lawsuits against manufacturers of the generic drugs, indicating they developed cancer from the tainted diabetes medication.

Sun Pharma indicates no adverse events have been reported in relation to the Riomet ER recall, and is notifying distributors and customers of the recall and arranging for the affected products’ return.

Consumers are advised to continue taking the recalled drugs and to contact their healthcare provider for advice on an alternative treatment. Consumers with questions can contact Sun Pharma by calling 1-800-818-4555 or via email sent to

The FDA requests any healthcare providers or consumers who experience adverse reactions or quality problems when using the affected drugs report the incident to the FDA MedWatch Adverse Event Reporting program.


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