The FDA found a second toxin that may cause cancer in three lots of valsartan, a commonly prescribed drug to control blood pressure and prevent heart failure.
Health regulators in the U.S., Canada and Europe, already have recalled several drugs made with Chinese firm Zhejiang Huahai Pharmaceutical's active ingredient valsartan after discovering a probable human carcinogen in the product.
The first toxin discovered was an impurity known as n-nitrosodimethylamine, or NDMA, a chemical once used to make rocket fuel and an unintended byproduct of several chemical reactions.
Now, the FDA is alerting the public to a second, unexpected impurity known as n-nitrosodiethylamine, or NDEA, a known animal and suspected human carcinogen.
The second toxin was found in three lots of Torrent Pharmaceuticals' recalled valsartan drug products. Torrent recalled those products Aug. 23.
The FDA's discovery is part of an expanded investigation into valsartan heart drugs. The agency is testing all products in the angiotensin II receptor blocker class to determine if they also have impurities.
So far, the FDA's testing shows that not all products made using Zhejiang Huahai's valsartan contain the newly found NDEA impurity.
"As we continue to investigate the root cause of the impurities found in products that contain valsartan, our scientists are testing these products to better understand these impurities and to ensure they're not present in other products," said FDA Commissioner Scott Gottlieb, MD. "We're also taking steps to make sure we’re providing stringent oversight of manufacturing processes to reduce the likelihood that impurities could be introduced into other products."