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Zithromax Increased Risk of Death After Donor Stem Cell Transplant

The FDA has released a new warning for Zithromax:

The antibiotic Zithromax (Zmax, azithromycin) should not be given long-term to prevent a certain inflammatory lung condition in patients with cancers of the blood or lymph nodes who undergo a donor stem cell transplant.

Results of a clinical trial found an increased rate of relapse in cancers affecting the blood and lymph nodes, including death, in these patients.

Azithromycin Side Effects

FDA Warning for deaths from Zithromax Azithromycin

Zithromax, generically known as Azithromycin and sometimes as Zmax, is an antibiotic used to treat many types of infections including respiratory infections, sexually transmitted diseases, skin infections and ear infections.

The FDA’s new warning includes a recommendation that Zithromax not be used as a long term prophylaxis treatment to reduce the risk of bronchiolitis obliterans. This use is off-label and not approved by the FDA. The new study showed a large increase in cancer recurrence and death among patients using the medication. The study was cancelled to protect study patients once it was clear Zithromax was harming patients in the study.

Zithromax for Bronchiolitis Obliterans Syndrome

Previous studies has suggested that long term Zithromax prescriptions could prevent bronchiolitis obliterans, a scarring and inflammation of the lungs that can occur in patients who have undergone hematopoietic stem cell transplantation (HSCT) treatment for cancer.

For the new study to test this hypothesis, 480 patients were randomly assigned to be treated with azithromycin or placebo for several years.  Unfortunately after just one year the relapse rate for those taking the antibiotic was 34% vs 22% for placebo. The survival rate dropped from 70% to 54% if taking Zithromax.

Due to these large increases in the risk of relapse and death, the study was stopped. The FDA has released this warning so patients and health care professionals can know the risks of off-label long term Zithromax for bronchiolitis obliterans prevention. The study found the risk of cancer recurrence and death both increased by 50% compared to placebo, a terrible outcome for the off-label use.