New Delhi: The US Food and Drug Administration (FDA) has updated the list of valsartan products under recall to incorporate those manufactured by India’s Hetero Labs Ltd for containing a probable cancer causing chemical.

FDA had last month recalled supplies of active ingredient valsartan, commonly used by people suffering from blood pressure problems, produced by Zhejiang Huahai Pharmaceutical Company based in eastern China, and listed on Shanghai’s stock exchange.

“FDA has updated the list of valsartan products under recall and the list of valsartan products not under recall to incorporate recalls of valsartan-containing products manufactured by Hetero Labs Limited, in India, labeled as Camber Pharmaceuticals Inc," FDA posted on its website on Thursday.

So far, more than 20 countries have recalled valsartan, which is alleged to contain the chemical NDMA (N-nitrosodimethylamine) impurity that poses a potential cancer risk.

NDMA is an organic carcinogen commonly used to make liquid rocket fuel, softeners and lubricants, among other products. It can also be unintentionally produced through certain chemical reactions and is a byproduct of some pesticide manufacturing, the making of rubber tires or fish processing.

The FDA found that NDMA exceeded the acceptable levels from the samples tested from Hetero Labs.

“Test results from Hetero Labs show the amount of NDMA found in its valsartan the active pharmaceutical ingredient (API) exceeds acceptable levels, although it is generally lower than the amount discovered in the API manufactured by Zhejiang," it further said.

Camber Pharmaceuticals is recalling certain valsartan tablets because they contain the impurity NDMA in the API, according to FDA. Hetero Labs manufactures the API for the Camber products using a process similar to Zhejiang Huahai Pharmaceuticals. However, FDA clarified that “not all Camber valsartan products distributed in the US are being recalled".

FDA is carrying out the investigations by testing samples of valsartan API and finished products to confirm the extent and amount of NDMA.

The agency has also contacted other manufacturers of valsartan API to determine if their manufacturing processes are at risk for the formation of NDMA, and is working with them to ensure NDMA is not present in future valsartan API.

Following the FDA alert, the Drug Controller General of India (DCGI) initiated investigations on Friday. DCGI had last month directed ports in India to ensure safety of the supplies of the drug imported from China before it enters the country, after the US regulator warned of a cancer-causing impurity.

Hetero Labs did not immediately respond to requests for comment.

Doctors in India cite safety concerns and advice immediate discontinuation of the drug.

“Valsartan has been important blood pressure drug with proven efficacy for patients with diabetes and heart disease. This unfortunate contamination means we should immediately discontinue it and replace it with safer alternatives. Physicians should especially be careful since it mostly comes in combination with other drugs in India," said Dr Anoop Misra, chairman, Fortis C-DOC.