Metformin Lawsuit Filed Over Cancer-Causing and Liver-Damaging Impurity

A generic metformin manufacturer faces a class action lawsuit brought on behalf individuals who purchased versions of the diabetes drug tainted with N-nitrosodimethylamine (NDMA); a chemical byproduct of the manufacturing process that is known to cause cancer and liver damage.

The complaint (PDF) was filed by Luis Sandoval in the U.S. District Court for the Central District of California on June 29, seeking class action status for claims against Heritage Pharmaceuticals, which was doing business as Avet Pharmaceuticals, Inc..

Sandoval, of California, has been taking metformin for the treatment of his diabetes since at least 2010. However, he only learned of the presence of high levels of NDMA in Avet’s generic metformin formulation earlier this year, when it was publicly reported that several versions of metformin may contain the cancer-causing and liver-damaging impurity.

NDMA is considered a human carcinogen, and has been found to contaminate other pharmaceutical drugs to manufacturing or design problems. A number of Zantac recalls and valsartan recalls have been issued over the past few years, after dangerously high levels of NDMA were detected in the popular heartburn and blood pressure medications, and users reported developing stomach cancer, bladder cancer, liver cancer and other injuries following long-term use.

Late last year, 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 that 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, the independent online pharmacy Valisure filed a citizen’s petition urging the FDA to issue metformin recalls, after independent testing found levels of NDMA in certain pills was higher than the agency’s recommended daily exposure threshold of 96 nanograms.

Specifically, Valisure found that Avet’s formulation of metformin contained 5.3 to nine times higher than the FDA’s recommended daily exposure limit, according to the lawsuit. To date, Avet has not issued a recall for its metformin products.

“Avet had not yet issued a recall of its defective metformin and continues to represent on its website that it manufactures ‘high quality generic medicines’,” Sandoval’s lawsuit states. “However, these representations are false, as Defendant’s metformin medication contains the carcinogenic impurity NDMA.”

Sandoval’s lawsuit seeks to have Avet reimburse purchasers of the drug for the money they paid, expecting a defect-free product, indicating he himself has paid a $35 per month copay since 2010. He presents claims of breach of warranty, unjust enrichment, fraudulent concealment, fraud, conversion, and violation of the California Unfair Competition Law.

NDMA In Zantac and Valsartan

Valisure is the same pharmacy which first raised alarms about the link between Zantac and cancer in September 2019, after finding that some pills contained 3,000,000 ng of NDMA. This led to further FDA testing, which confirmed the high levels were present in virtually all Zantac products and their generic equivalents, resulting in a widespread, and still ongoing, Zantac recall.

Concerns over NDMA drug contamination in pharmaceutical drugs began to emerge in 2018, with an investigation into a number of generic blood pressure drugs that were found to contain high levels of the chemical. This led to several rounds of recalls for valsartan, losartan and irbesartan, and investigations suggested that NDMC may have contaminated the drugs as a by-product of changes in the generic drug manufacturing process.

In response to concerns about the cancer risk with valsartan and other similar drugs, and the possibility of shortages for the hypertension drugs, the FDA established a permissible daily limit for NDMA at 96 nanograms, requiring pills that may expose users to more of the carcinogen to be recalled.

While drug makers and federal regulators indicate they are continuing to investigate the underlying cause of both the NDMA contamination, many consumers diagnosed with cancer in recent years are now pursuing valsartan lawsuits and Zantac lawsuits, alleging they may have avoided a cancer diagnosis if other treatments had been used.