OTTAWA – Health Canada is warning Canadians of the potential risk of cancer relapse in patients with cancer of the blood and lymph nodes who have undergone stem cell transplant and are taking long-term azithromycin (Zithromax).
The drug was being tested in clinical trials outside Canada with the goal of preventing a certain type of inflammatory lung condition called bronchiolitis obliterans syndrome. Cancer patients who have undergone stem cell transplants from donors are at risk of developing this condition, which causes scarring of the lungs and difficulty breathing. However, a clinical trial in France has found an increased risk of cancer recurrence with long-term use of azithromycin in stem cell transplant patients.
As a result, the U.S. Food and Drug Administration (FDA) issued a warning that azithromycin should not be given long-term to prevent a certain inflammatory lung condition in this specific patient population.
The Canadian label for azithromycin does not include an indication for use to prevent bronchiolitis obliterans syndrome following stem cell transplants. Azithromycin has been used for its approved indications for more than 20 years. Those approved indications are not affected by this warning.
Health Canada has not received any reports of Canadian cases of cancer relapse in stem cell transplant patients taking azithromycin. However, the Department will continue to monitor the issue and take appropriate action, if necessary. If any new safety concerns are identified, Health Canada will update Canadians, including health professionals, as required.
What you should do
If you are using azithromycin and have concerns, talk to your doctor.
What industry professionals should do
- Avoid prescribing long-term azithromycin for prophylaxis of bronchiolitis obliterans syndrome to new patients following stem cell transplants for blood or lymph node cancer treatments.
- Consider the risks and benefits for patients already being treated with azithromycin.
- Advise patients being treated with azithromycin treatment following stem cell treatment for cancer of new safety concerns.
Report health or safety concerns
To report a side effect to a health product to Health Canada:
- Call toll-free at 1-866-234-2345
- Visit Health Canada’s Web page on Adverse Reaction Reporting for information on how to report online, by mail or by fax.
For more information
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