A fast-tracked study looked at short-term cancer risk for those taking the recalled medications.
A worldwide recall earlier this year removed several common drugs for high blood pressure containing valsartan from the market due to a potential cancer risk.
But patients prescribed these drugs for high blood pressure or heart failure were left with no clear picture of how big a risk their medications may have posed.
Now, a new fast-tracked study suggests that there’s no “markedly increased short-term overall risk of cancer” among people who had taken valsartan contaminated with N-nitrosodimethylamine, or NDMA.
However, the researchers point out that additional studies with longer follow-up of patients are needed to assess the long-term cancer risk.
This news, though, is followed by the U.S. Food and Drug Administration’s (FDA) finding a second potentially cancer-causing chemical in valsartan products recalled in August.
In July, the FDA and other agencies around the world issued a voluntary recall of certain products containing valsartan due to the presence of an “impurity.”
The impurity, NDMA, is classified as a probable human carcinogen based on laboratory tests.
The long-term risks posed by valsartan-containing drugs contaminated with NDMA is unclear, and depends in part upon the amount of the impurity consumed.
FDA scientists estimated in July that if 8,000 people took the highest dose of valsartan — 320 milligrams — from the recalled batches every day for four years, there may be one additional case of cancer over the lifetimes of these people.
The presence of NDMA in the recalled products seems to be due to a change in 2012 in how the drugs were made by Zhejiang Huahai Pharmaceutical Co. in Linhai, China, wrote the authors of the study.
The recall only affected products made at this facility — initially valsartan from Major Pharmaceuticals, Solco Healthcare, and Teva Pharmaceutical Industries Ltd., as well as valsartan/hydrochlorothiazide from Solco and Teva.
Last month, the FDA updated the full recall list.
In the new study, researchers looked at data on 5,150 Danish patients who filled a prescription for a valsartan-containing medication between 2012 and 2018.
Researchers tracked which valsartan drug product people used and whether they developed cancer during the 4.6-year average follow-up period.
The researchers found that exposure to potentially contaminated valsartan products wasn’t associated with an increased short-term overall risk of cancer, compared with exposure to valsartan products unlikely to be contaminated with NDMA.
The study was published September 12 in the medical journal The BMJ.
When the researchers looked at specific types of cancer, they found increased risks for colorectal and uterine cancers. These results, though, weren’t statistically significant.
The researchers wrote that a more cautious interpretation of the results “highlights that our study cannot confidently rule out an increased risk from exposure to NDMA.”
In addition, information on how much NDMA was in each valsartan tablet wasn’t available. This makes it impossible to know each person’s exposure level.
Jean Moon, PharmD, an associate professor in the College of Pharmacy at the University of Minnesota, said the study “should provide reassurance to patient concerns about their short-term cancer risk.”
But Dr. Theodore Kurtz, a clinical pathologist at the University of California, San Francisco, who studies high blood pressure, was less optimistic.
“If I happened to be a patient who took valsartan that contained NDMA, this study would not alleviate my concerns,” he said.
Because of the short follow-up period, the study only addressed short-term cancer risks.
“Further analysis would need to be conducted to fully understand the long-term impact,” said Moon.
The quick turnaround for the study was possible because Denmark has four national health registries that track individual prescription drug use, cancer occurrence, and hospital diagnoses.
A day after the release of the new study, the FDA announced that its testing had found an “additional unexpected impurity” in three lots of valsartan drug products from Torrent Pharmaceuticals.
This second impurity is N-Nitrosodiethylamine, “a known animal and suspected human carcinogen.”
These products were included in the Zhejiang Huahai Pharmaceutical’s August recall of valsartan products.
The FDA recommends that people taking valsartan for high blood pressure or heart failure continue to do so until they can speak with their doctor or pharmacist.
Even if your medication is part of the recall, the agency says you should continue to take your medication until your doctor can find a suitable alternative.
Kurtz said this might include choosing only drugs made in specific locations.
“I personally try to avoid using medicines manufactured in certain countries outside the United States,” said Kurtz, “although I understand that due to cost factors, this is not possible for many patients.”
Moon said “events like these are always concerning.”
She recommends that people taking valsartan share their questions and concerns with their physician and pharmacist.
She also suggests making sure they can contact you, if needed.
“If your pharmacy or physician’s office is trying to contact you, it is likely they are trying to convey important information about your medications to you,” said Moon. “That means the pharmacy and physician’s office will need your most up-to-date contact information.”
In a preliminary study, researchers found that exposure to potentially contaminated valsartan products (used to treat high blood pressure) was not associated with an increased short-term overall risk of cancer, as compared with exposure to valsartan products unlikely to be contaminated with NDMA.
However, experts caution more study is needed.
Additionally, the FDA has found additional impurities that are linked to a known carcinogen in animals and suspected in humans.
Currently the FDA is recommending that people taking valsartan continue to do so until they can speak with their doctor or pharmacist.