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Some drugs containing valsartan, a blood pressure medication, may contain a second substance that can cause cancer, according to Health Canada.
All drugs containing valsartan, manufactured by Zhejiang Huahai Pharmaceuticals in China, were recalled to Canada after a first impurity, N-nitrosodimethylamine (NDMA), was identified earlier this summer. NDMA is classified as probably carcinogenic to humans, which means that long-term exposure could increase the risk of cancer, according to regulatory agencies.
Medications containing valsartan treat high blood pressure and help prevent heart attacks and strokes. They are also used by patients who have had heart failure or a recent heart attack.
On Thursday, Health Canada said that a second impurity, called N-nitrosodiethylamine (NDEA), had also been found in the valsartan manufactured by Chinese society.
"The new information on NDEA is very limited at this time, and Health Canada is assessing the problem and will inform Canadians as new information becomes available," the regulator said.
Health Canada has stated that patients taking valsartan medications should:
- Ask their pharmacist if they do not know if they are using a recalled product.
- Contact their health care provider as soon as possible to discuss treatment options if they have used an affected product. Pharmacists may be able to provide a non-recalled product or physicians may prescribe another drug.
- Continue taking valsartan medication unless your health care provider has been advised to stop taking it. Since cancer risk is related to long-term exposure to NDMA and NDEA impurities, there is no immediate risk to health and patients can continue to take this medication to discuss treatment options with their partner. health care provider. .
Contact your health care provider if you have taken any of the recalled valsartan products and have health problems.
Estimated lifetime cancer risk
Earlier this week, Health Canada released its assessment of the health risks of valsartan products containing NDMA.
Given that the longest-affected products had been sold in Canada for three years, Health Canada estimated that among those taking the highest dose of valsartan (230 mg / day), the increased risk of cancer during their lifetime cancer for 11,600 people taking the product.
To put the estimate in context, nearly one in two Canadians is expected to develop cancer during their lifetime.
For the lowest dose of valsartan (40 mg), Health Canada estimated that the increased potential risk of cancer during its lifetime may be an additional case for 93,400 people taking the product.
The two European medical agencies and the US Food and Drug Administration also removed valsartan products from the market due to suspected NDMA contamination.
In this week's issue of the BMJ, Danish researchers concluded that the recalled antihypertensive drugs were not related to an increased risk of cancer in the short term, according to data from Danish health registries.
The researchers used prescription files to classify patients into two groups:
- Those never exposed to NDMA.
- Those who probably or probably prescribe NDMA-contaminated valsartan products.
People were followed on average for 4.6 years.
"Our findings do not imply a marked increase in short-term cancer risk in NDMA-infected valsartan users." However, uncertainty persists about single-cancer outcomes and studies with follow-up. longer are needed to assess long-term cancer risk. " Kristensen from the University of Southern Denmark in Odense and her co-authors have concluded.
A review editorial published with the study indicates that regulators have taken swift action, but that exposed patients still need long-term follow-up.
Dr. Satjit Bhusri, a cardiologist at Lenox Hill Hospital in New York, agreed.
"This study could reassure people already exposed to this additive, but this should not prevent patients from submitting to routine cancer screening and the future avoidance of this additive," Bhusri told HealthDay News.
Cardiologists and pharmacists said different alternatives exist for the recalled products.
According to Health Canada, as of August 18, the list of recalled products included drugs from Teva Canada, Sandoz, Sanis, Pro Doc Ltd. and Sivem Pharmaceuticals. The regulator has also updated its list of non-recalled products.
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