An online pharmacy company has notified the U.S. Food & Drug Administration (FDA) that yet another carcinogen could be lurking in valsartan, a widely used medication indicated to treat high blood pressure and heart failure.
Valisure, which is licensed to sell prescription drugs in 37 states, says its own tests detected dimethylformamide, or DMF, in valsartan tablets marketed by several drug makers.
The chemical apparently turned up in Diovan, the brand-name version of valsartan manufactured by Novartis. DMF was also detected in generic tables, including those made by Alembic Pharmaceuticals Ltd. and Macleods Pharmaceuticals Ltd. Both companies’ products are included on a list of drugs the FDA deemed safe amid ongoing recalls for generic medications that could be tainted with other cancer-causing substances.
The Valisure tests detected DMF levels ranging from 8 nanograms per pill to over 100,000.
According to Bloomberg News, the World Health Organization declared DMF a probable human carcinogen just last year. The FDA considers the chemical a Class 2 solvent, a designation that mandates it be “limited in pharmaceutical products because of its inherent toxicity”.
“Novartis cannot currently fully exclude the possibility that traces of DMF (within acceptable limits) may have been present in materials” provided to their suppliers, a company spokesperson wrote in an email to Bloomberg.
Valisure has asked the FDA to issue a valsartan recall for the affected products. The company also requested that the agency lower the acceptable intake of DMF from its current level of 8,800,000 nanograms to less than 1,000 nanograms.
An FDA representative told CNBC that it is reviewing the Valisure findings and will notify the online pharmacy directly when it reaches a conclusion. The official also warned patients to continue taking valsartan, as stopping treatment abruptly could lead to sudden and serious cardiovascular events.
So far, it’s not clear how the valsartan tablets became contaminated. Novartis indicated that it does not use DMF in its manufacturing process, but acknowledged that its suppliers might buy from other companies that do. There is also a possibility that DMF resulted from chemical reactions that occurred during production.
DMF is the fourth potentially cancer-causing substance detected in valsartan and other widely-used heart and blood pressure drugs.
Multiple generic drug makers in nearly two dozen countries began recalling valsartan last summer, after tests turned up the first of three carcinogenic nitrosamines in active pharmaceutical ingredients sourced from China-based Zhejiang Huahai Pharmaceutical Co., Ltd. and Hetero Labs of India. The recalls eventually affected other Angiotensin II Receptor Blockers (ARB), including generic losartan and irbesartan products.
The FDA maintains that the risk of cancer from the recalled ARBs is low. However, Valisure suggested the risk could be exacerbated if DMF and a nitrosamine were both present in valsartan.
The ongoing recalls have raised concerns about the safety of prescription medications sold in the United States, especially those containing ingredients sourced from overseas suppliers. According to Bloomberg, the American Medical Association recently announced the launch of a new study to determine whether independent testing and other actions should be implemented to ensure the safety of nation’s drug supply.
“I think we make assumptions that drugs, once they’re approved by the FDA or once they’re on the market for patients, that they’re OK and they’re all the same,” said Suma Thomas, a cardiologist at the Cleveland Clinic who pushed for the study. “We need more knowledge.”