The European Medicines Agency has issued an update on its investigation into the health risks of taking valsartan medicines containing an impurity that may have carcinogenic potential, revealing that affected batches could lead to one extra case of cancer per 5,000 patients who take them.

Valsartan is an angiotensin-II-receptor antagonist used to treat high blood pressure, recent heart attack and heart failure. Batches of the drug that were made by Dexcel Pharma and Accord Healthcare were recalled by the Medicines and Healthcare products Regulatory Agency (MHRA) in early July as part of a Europe-wide recall.

This followed reports that an impurity (N-nitrosodimethylamine, or NDMA) with possible carcinogenic potential was found in the active substance manufactured by Zhejiang Huahai Pharmaceuticals in China, due to changes to the company’s manufacturing process.

There have recently been reports that the recall of the drug has “gone global”, with countries such as China, Taiwan and South Korea joining the US and EU in stopping the drug being given to patients.

EMA commented on its investigation into the potential harmful effects of taking affected valsartan medicines: “Following a preliminary evaluation, EMA estimates that there could be one extra case of cancer for every 5,000 patients taking the affected medicines at the highest valsartan dose (320mg) every day for seven years. This is based on average levels of this impurity detected in the active substance from Zhejiang Huahai Pharmaceuticals (60 parts per million).”

This risk is based on animal studies, EMA said, adding that it “should be considered in the context of the lifetime risk of cancer in the EU (1 in 3) and NDMA exposure from other countries”.

“It is important to note that there is no immediate risk to patients. Patients taking the affected medicines who have not yet switched to an alternative should not stop taking their medicines without consulting their doctor or pharmacist,” the Agency said.

EMA said that tests are ongoing and that when more data is available it will be able to provide more information on the potential risks.