Only a few months ago, government health authorities in Europe and the U.S. issued recalls for the blood pressure medication valsartan over concerns of the presence of a carcinogenic industrial chemical known as N-nitrosodimethylamine (NDMA).
This past week, Danish researchers offered limited reassurance over the cancer risks of NDMA-tainted valsartan. However, on Thursday, the U.S. Food and Drug Administration announced the discovery of a different chemical contamination.
On September 13th, the regulatory agency announced that three lots of valsartan-containing drugs made by Torrent Pharmaceuticals were found to contain N-Nitrosodiethylamine (NDEA). Both chemicals are classified as nitrosamines, a group of organic compounds that occur as a result high-temperature cooking, the manufacture of latex and other industrial processes.
The carcinogenicity of NDMA in humans is not 100% certain. While it is known (and is used) to cause cancer in laboratory animals for research purposes, the EPA classifies it as a “probable human carcinogen.” It is nonetheless extremely toxic, particularly to the liver, where exposure can result in fibrosis.
Low levels of NDMA are found in smoked or cured meats and can occur as the result of high-temperature cooking methods. NDMA is an industrial byproduct from the manufacturing of certain pesticides and rubber as well as fish processing. It is also employed in the production of liquid rocket fuel.
NDEA occurs in tobacco smoke. Classified as a Group 2A carcinogen by the World Health Organization’s International Agency for Research on Cancer (IARC), this particular chemical is mutagenic, meaning that exposure can result in genetic alterations (i.e., DNA). Such mutations can result in the formation of malignant tumors as well as affect the reproductive system.
In the recent study published in the British Medical Journal, the Danish research team looked at a total of 5,150 patients age 40 or over who had no history of cancer and had been taking valsartan for a period averaging approximately 4-1/2 years. Among study participants who had not been exposed to NDMA, there were 104 cases of cancer. However, among those who had taken tainted valsartan, 198 had developed cancer.
The researchers concluded that “results do not imply a markedly increased short-term overall risk of cancer in users of valsartan contaminated with NDMA.” However, they cautioned that “uncertainty persists about single cancer outcomes, and studies with longer follow-up are needed to assess long-term cancer risk.”
The contaminated valsartan originated from a drugmaker known as Zhejiang Huahai Pharmaceuticals, located in Linhai. The contamination dates from around 2012 and appears to be connected to a change in the manufacturing process that was made at that time. NDMA is considered to be one of the most potent carcinogens known. Considering that NDEA is a component of cigarette smoke, the FDA's recent discovery of the chemical’s presence in valsartan is not reassuring, despite the conclusions of the Danish study.
It should be noted that not all versions of valsartan have been found to be tainted with NDMA, and so far, only valsartan medications coming from Torrent Pharamceuticals appear to contain NDEA. The FDA is keeping regularly-updated lists of which valsartan products have been recalled and which have not.