Valsartan contaminated with the impurity N-nitrosodimethylamine (NDMA) does not increase the short-term risk of overall cancer, according to research published in The BMJ
The cohort study looked at over 5,000 Danish patients with no history of cancer who were using valsartan on 1 January 2012, or who initiated use between 1 January 2012 and 30 June 2017. The patients were followed for one year after cohort entry until 30 June 2018 or until they migrated, were diagnosed with cancer, or died.
Just over 100 of those individuals not exposed to NDMA were diagnosed with cancer during that time period, compared with 198 patients who were exposed to the impurity, representing a 9% increased risk of overall cancer and no evidence of a dose–response relation.
When looking at single cancers it was found that exposure to NDMA was associated with an increased risk of colorectal cancer and uterine cancer, but neither these nor any of the other single cancer outcomes reached clinical significance.
Despite not finding any evidence of a marked increase in the short overall risk of cancer, the researchers said that they could not exclude a modest association. “Further studies are needed to fully elucidate the health effects of NDMA contaminated valsartan products,” they concluded.
At the beginning of July 2018, pharmacies across the EU were advised to recall all batches of valsartan-containing medicines manufactured by Dexcel Pharma Ltd and Accord Healthcare (previously known as Actavis Group), after an impurity was unexpectedly identified as part of Zheijang Huahai Pharmaceuticals’ manufacturing process.
NDMA, which, according to test results, could cause cancer with long-term use, is classified as a probable human carcinogen by the International Agency for Research on Cancer.
The agency emphasises that NDMA “should be regarded for practical purposes as if it were carcinogenic to humans”.
 PottegÃ¥rd A, Kristensen K, Thomsen M, et al. Use of N-nitrosodimethylamine (NDMA) contaminated valsartan products and risk of cancer: Danish nationwide cohort study. BMJ 2018;362:k3851 doi: 10.1136/bmj.k3851