Z-pack FDA Warnings

Z-pack – azithromycin – could lead to deadly heart rhythms

The popular antibiotic Azithromycin could trigger a potentially deadly irregular heart rhythm for some patients, the FDA warned in March 2013.

Sold as Zithromax, Zmax,  a “Z-Pack” is prescribed to treat bacterial infections such as bronchitis, pneumonia, ear infections and more.

The FDA has warned that the pills can cause abnormal changes in the heart’s electrical activity that could lead to a fatal heart rhythm. Patients at greatest risk are those with known risk factors such as existing QT interval prolongation, low blood levels of potassium or magnesium, a slower than normal heart rate, or those who use  certain drugs to treat abnormal heart rhythms.

In a March 12, 2013 update, the FDA stated: “Health care professionals should consider the risk of fatal heart rhythms with azithromycin when considering treatment options for patients who are already at risk for cardiovascular events.”

A May 2012 study triggered the new guidance, along with, another study by Pfizer, the antibiotic’s maker, which assessed risks to electrical activity of the heart in those taking azithromycin.

A New England Journal of Medicine study last May – which was paid for by the National Heart, Lung and Blood Institute – found there would be 47 extra heart-related deaths per one million course of treatment with five days of Zithromax, as compared to 10 days of amoxicillin and other antibiotics. The FDA said risks of cardiovascular death associated with levofloxacin (Levaquin) treatment were similar to those associated with azithromycin treatment.

Dr. Harlan Krumholze, a Yale University health outcomes specialist who was not involved  in the study, downplayed its findings. He told the AP last May: “People need to recognize that the overall risk is low.” He also posited that more research was needed, but said that patients with heart disease, “[s]hould probably be steered away” from Zithromax.

The FDA also issued a post-study statement in May 2012 that the agency was aware of the findings, and it would review the results and communicate any new information.

The AP also reported that Zithromax sales totaled $464 million in 2011, according to health care information company IMS Health.


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