Zhejiang Huahai Pharmaceutical Co. Ltd. has ceased shipments of its valsartan high blood pressure and heart medicine and initiated voluntary recalls in domestic and foreign markets after discovering a cancer-causing substance in the drug, Xinhua News reported, citing a statement from China's State Drug Administration.

Xinhua said in a July 30 report that Zhejiang Huahai told state regulators July 6 that traces of the cancer-causing impurity known as N-nitrosodimethylamine, or NDMA, were found in its products for export. The company supplies active pharmaceutical ingredients, or APIs, for valsartan. The drug was developed by Novartis AG, marketed under the name Diovan.

The State Drug Administration advised patients to continue taking the valsartan medication unless a doctor recommends otherwise. While NDMA has been classified as a carcinogen by European regulators, little evidence is available to confirm the substance causes cancer in humans. Recalls and other measures are taken out of precaution and drugs containing NDMA are not expected to pose a severe risk to patients' health, the regulator said.

Following risk assessment actions conducted by other health agencies abroad, the Chinese drug regulator screened products manufactured by seven valsartan API suppliers in the country, including Zhejiang Huahai, the news agency reported. The other six manufacturers were cleared, Xinhua added, citing a spokesperson for the State Drug Administration.

Earlier in July, the European Medicines Agency said it was conducting a review of certain high blood pressure and heart medicines for the possible contamination of NDMA. This prompted a recall across the EU of medicines containing valsartan.

The U.S. Food and Drug Administration also disclosed that several companies — including Teva Pharmaceutical Industries Ltd., Major Pharmaceuticals, Inc. and Solco Healthcare — voluntarily recalled their products with valsartan supplied by an undisclosed third-party.