As part of an ongoing FDA investigation, six drug repackagers are recalling their valsartan HCTZ blood pressure medications due to a potential contamination increasing the risk of cancer.

As of July 27, these companies have been added to a recent voluntary recall of valsartan HCTZ generic blood pressure medications. The recalls are prompted by an investigation by the U.S. Food and Drug Administration (FDA) following reports that these medications may contain N-nitrosodimethylamine (NDMA), a contaminant and possible human carcinogen.

Companies affected by this recall include Bryant Ranch Prepack Inc., H. J. Harkins Company Inc., Lake Erie Medical (doing business as Quality Care Products LLC), NuCare Pharmaceuticals Inc., Northwind Pharmaceuticals, and Proficient Rx.

Valsartan HCTZ blood pressure medications are used to treat blood pressure in adults and children age six and up. The FDA has also approved the drug for use in adults to treat heart failure and for use in patients who recently had a heart attack to reduce the risk of death. Valsartan HCTZ medications work by reducing the constriction of blood vessels, improving cardiac health and allowing blood to flow more freely.

Not all valsartan HCTZ medications are affected by the recall, and brand name Diovan products have also not been included.

“We have carefully assessed the valsartan-containing medications sold in the United States, and we’ve found that the valsartan sold by these specific companies does not meet our safety standards,” said the director of the FDA’s Center for Drug Evaluation and Research, Janet Woodcock. “This is why we’ve asked these companies to take immediate action to protect patients.”

Although NDMA has not been 100 percent confirmed as a human carcinogen, the chemical has been found to increase the risk of cancer in animal studies, prompting the U.S. Environmental Protection Agency (EPA) to classify the chemical as a probable human carcinogen.

It is considered reasonable safe to consume up to 96 nanograms of NDMA a day. The FDA estimates that if 100,000 took this amount of NDMA for the rest of their life, it would result in less than one additional case of cancer for every 100,000 people. “To put this in context, currently one out of every three people in the US will experience cancer in their lifetime,” the FDA says in the valsartan HCTZ announcement.

The recalled valsartan HCTZ medications have been found to contain above the acceptable established threshold. The FDA estimates that if 8,000 people took the highest dose of one of these valsartan HCTZ medications for four years, it would result in one additional case of cancer over the lifetimes of the 8,000 people. “This assessment led to FDA’s decision to have these batches recalled,” the FDA valsartan HCTZ page states.

The FDA is currently conducting an ongoing review of valsartan HCTZ medications to determine the levels of NDMA, the risk patients may face, and the next steps to reduce or eliminate NDMA in these medications.

The agency encourages patients to consult with their doctor during the ongoing investigation. Since not all valsartan HCTZ products are affected, pharmacists may be able to refill a medication from batches not affected by the recall.