Once cleared by the FDA of a probable carcinogen, generic diabetes med metformin has now been the target of a growing number of recalls. This week, a seventh drugmaker has joined the metformin recall parade after finding high levels of a potential cancer-causing contaminant.

Sun Pharma recalled one lot of its Riomet ER, an extended-release version of the common diabetes med, after testing showed high levels of N-nitrosodimethylamine (NDMA), the drugmaker said Wednesday.

The recalled lot contains 747 bottles of the drug with an expiration date of October 2021, Sun said in a release. 

Sun is now the seventh drugmaker to launch voluntary recalls of their versions of metformin after the FDA earlier this year found high levels of NDMA, a contaminant connected to global recalls of “sartan”-based heart pressure drugs and heartburn med Zantac, in tested lots. 

In August, New Jersey-based Bayshore Pharmaceuticals recalled one lot each of its 500- and 750-milligram extended-release metformin after the FDA found high levels of NDMA in tested samples.

Lupin Pharmaceuticals in July pulled all lots of its extended-release metformin after discovering high levels of NDMA in their sample lots. Just days before that, the FDA had said Virginia-based Granules Pharmaceuticals would pull its own version of extended-release metformin based on the same contamination concerns.

The FDA in May asked five drugmakers, including Lupin, to withdraw their products from shelves after identifying abnormally high NDMA.

The FDA said it would work with the companies to determine whether the recommended recalls would cause a shortage in the U.S. The move didn’t apply to metformin’s immediate-release formulation, and the FDA specified that “there are additional manufacturers of the metformin ER formulation that supply a significant portion of the U.S. market, and their products are not being recalled.”

The other drugmakers included Apotex, Teva, Amneal and Marksans, all of which launched their own recalls in early June.