An online pharmacy told U.S. regulators it found another cancer-causing chemical in widely prescribed blood-pressure pills, raising new questions about a complex global web of companies that produces medicine for millions of people.
A solvent called dimethylformamide was discovered in the drug valsartan made by several companies, including Swiss pharmaceutical giant Novartis, according to a filing last week to the Food and Drug Administration by New Haven, Conn.-based Valisure.
DMF, as the solvent is known, is classified by the World Health Organization as a probable carcinogen.
Dozens of forms of generic valsartan have been recalled since July 2018, when the carcinogenic chemical N-Nitrosodimethylamine, or NDMA, was detected in a version of the drug made by a Chinese company. Valsartan is a decades-old treatment for hypertension that is frequently combined with other medicines into a single pill.
Valisure found DMF in valsartan that is still on the market in the U.S., including in medicines the FDA had highlighted as alternatives to recalled drugs. The findings could complicate the agency’s efforts to pull tainted drugs from pharmacies while informing doctors and patients which medications are safe. DMF is the fourth potential carcinogen to be found in batches of the heart pills.
Some drugmakers whose pills tested positive for DMF said that neither they nor the outside companies that produce active ingredients for their drugs use the solvent, though some indicated they don’t have complete visibility into their supply chain.
“Novartis cannot currently fully exclude the possibility that traces of DMF (within acceptable limits) may have been present in materials” provided to their suppliers, said Novartis spokesman Eric Althoff in an email.
The FDA is investigating how the recalled medications were contaminated. The possibility that the use of DMF in the manufacturing process led to chemical reactions that formed the other carcinogens has been raised by regulators.
The agency will evaluate Valisure’s study, said spokesman Jeremy Kahn. Patients should keep taking their blood-pressure medication even if it is recalled, the FDA says, until they can talk to their doctor. Suddenly stopping such drugs could cause harm.
Valisure’s findings suggest the manufacturing of drugs may be more porous than commonly understood.
When drugs are made, the initial raw materials may need to change form before they go into a pill.
“Medicines are kind of like used cars: By the time you get it it’s already five or six years old, it’s touched hundreds of hands and it’s got 100,000 miles on it,” Valisure Chief Executive Officer David Light said in an interview.
