In the wake of a worldwide recall, patients prescribed several common drugs that contain valsartan must be wondering exactly how much of a cancer risk their medication may have posed.
Now, an expedited study suggests that there is no markedly increased short-term risk of overall cancer among users of valsartan contaminated with the impurity, N-nitrosodimethylamine or NDMA. However, more research is needed to assess long-term risk.
The study was published in the medical journal BMJ on Wednesday.
Certain products containing the valsartan ingredient, used to treat high blood pressure and heart failure, were recalled in July by the US Food and Drug Administration and other agencies around the worlddue to an "impurity" in the drug that poses a potential cancer risk.
That impurity, NDMA, has been classified as a probable human carcinogen, based on lab test results. It may have contaminated certain valsartan batches since 2012.
As of now, the long-term risks posed by NDMA found in certain valsartan-containing drugs remain somewhat unknown, and the amount of NDMA consumed plays a role in that risk.
In an assessment in July, FDA scientists estimated that if 8,000 people took the highest valsartan dose, at 320 milligrams, from the recalled batches daily for four years, there may be one additional case of cancer over the lifetimes of these 8,000 people.
Valsartan is off patent and is used as a component of other generic medicines, but not all medicines containing the ingredient are involved in the recent recall.
The researchers noted in the new study that the NDMA contamination, which exceeded regular exposure limits, was specific to drug products manufactured by Zhejiang Huahai Pharmaceuticals in Linhai, China. The contamination seemed to be related to a change in the manufacturing process that was implemented in 2012, according to the researchers.
The specific medicines included in the FDA voluntary recall are valsartan from Major Pharmacuticals, Solco Healthcare and Teva Pharmaceuticals Industries, as well as valsartan/hydrochlorothiazide from Solco and Teva.
The full recall list was updated last month.