Medicines which treat blood pressure and heart failure but pose possible human cancer risks have remained on sale at many drugstores in Vietnam, although health authorities had ordered to recall them nearly a week earlier, raising questions about regulation enforcement.

Vietnam’s Agency of Drug Administration introduced a national ban on the sale of 23 drugs that contain a foreign-made potential cancer-causing substance called valsartan on July 13.

Valsartan, supplied by China’s Zhejiang Huahai Pharmaceuticals in Linhai, has an impurity known as N-Nitrosodimethylamine (NDMA) – an organic chemical that belongs to a family of potent carcinogens.

It used to be found in rocket fuel, lubricants and softeners, according to the U.S. Environmental Protection Agency’s January 2014 fact sheet.

Animal studies reveal that NDMA can create tumors in the liver, kidney and blood vessels, the sheet said.

The medicines covered by the recall come mainly from Poland, Spain, India, Pakistan and Bulgaria.

It is noteworthy that the drug administration agency’s decision does not specify the date by which the call is completed, and this may partly explain why the medicines have been obtainable at a number of pharmacists and the recall progress seems slow.

During a visit at a drugstore on Phan Dinh Phung Street in Phu Nhuan District of Ho Chi Minh City on July 18, Tuoi Tre (Youth) newspaper reporters found around ten boxes of valsartan medicine placed in a drawer rather on a shelf.

For each time of being asked, the pharmacist gave a different price for the same box.

At another shop in the metropolis’ District 5, the clerk said Valsartan STADA, also subjected to the recall, was still available on the same day.

In Hanoi, a drugstore said Wednesday it had run out of valsartan tablets several days earlier because a customer had purchased it.

“If you want to buy it, just write the drug’s name down here. I’ll order it tomorrow, you’ll get the exactly the same drug you need,” the shop’s owner said.

Vietnam’s move is predated several days by an international recall of batches of valsartan-containing drug started in 22 countries.