China’s top health authority has ordered all medical institutions in China to stop using drugs for treating high blood pressure that contain an impurity that could cause cancer, and ordered them to cooperate with drug authorities in a product recall.

The National Health Commission made the announcement on July 30 following a statement by the State Drug Administration on July 29 calling on local drug authorities across China to supervise the recall of all medicines containing valsartan－the active ingredient in certain blood pressure medicines－made by Zhejiang Huahai Pharmaceutical Co in Linhai, Zhejiang province. Valsartan supplied by other companies is not part of the recall.

The company reported on July 6 that it had found traces of NDMA in the valsartan it produced, and began recalling affected products in China and overseas, the SDA said.

Five companies that make blood pressure medicines containing the valsartan supplied by Huahai in China are recalling those medicines, it said.

In its statement on July 30, the National Health Commission said hospitals can safely use drugs containing other makers’ valsartan, or they can prescribe different drugs for patients.

Medical institutions should submit information about the drug recall to local health and drug regulators, it said.

Cancer-causing impurities found in Huahai Pharmaceutical’s valsartan stirred much public attention recently, as the drug is commonly used to treat high blood pressure－or hypertension－in China.

The SDA said on July 29 that only small traces of NDMA had been found in the final products, and there is little evidence showing it causes cancer in humans, though the link to cancer in animals may be stronger. It said patients who have taken tainted drugs will not likely have serious health consequences.

Yu Zhenqiu, director of the hypertension department at Beijing Anzhen Hospital, said the recall of some valsartan products from the market will have little impact on the treatment of patients in China, as there are dozens of drugs available on the market.

“Patients who have taken affected drugs can switch to valsartan drugs made by other companies, or switch to other hypertension drugs, but it must be under the guidance of doctors,” he said.

Xu Shuxiang, secretary-general of a drug research group－the China News of Drug Information Association－said that, based on the information disclosed by Huahai and the administration, the traces of NDMA should not harm anyone’s health. Drug authorities insisted recalling all affected drugs as a precaution.

“It is puzzling that such an impurity was found in Huahai’s products, as it is one of the few pharmaceutical companies in China that exports to developed countries,” he said.

Huahai said earlier that the unexpected discovery of NDMA was probably the result of changing manufacturing techniques, and no NDMA was found in other products of the company. It had completed its recall of its valsartan in China last week.

Following reports about the impurity, the European Union began recalling medicines containing the company’s valsartan in early July, while the United States took similar action on July 14, according to Reuters.

After reporting the NDMA, the company contacted drug regulators in various countries to which its products are exported, but regulators in different places evaluated the situation differently, so recall dates varied, the company said in a statement on July 30.