Z-Pak's fatal risks don't apply to the average patient, new study finds

The popular Z-Pak antibiotic, linked to heart-rhythm problems in March, may not be risky for the average patient, a new study suggests. The FDA maintains that patients with certain risk factors--those with known arrhythmias, heart damage, and underlying heart disease--should be careful with the Pfizer ($PFE) antibiotic, sold under the brand name Zithromax. But patients with healthy hearts may not need to worry.

The new study of antibiotic use in 1 million young and middle-aged patients in Denmark found that Zithromax was linked with a nearly threefold increase in the risk of dying from heart problems during the 5-day treatment cycle. But that's compared with patients who weren't using antibiotics. The researchers found a similar increase in death risk for patients using penicillin.

So the researchers theorize that the patients' illnesses, rather than the drugs, may be the reason for the increase in risk. "This indicates that the increased risk compared with no use of antibiotics is explained by an increased risk of cardiovascular death associated with acute infection, rather than with azithromycin," lead author Henrik Svanström told Heartwire.

In other words, the 2012 study that raised FDA's eyebrows showed that Zithromax affects "cardiovascular mortality in a selected population," Svanström said, while his study shows that a similar effect "is not present in the general population."

Other experts weren't quite so categorical, though they did generally agree with the researchers' conclusions; Dr. David Juurlink of the Institute for Clinical Evaluative Sciences in Toronto told the news service that although some of the increased risk "might be explained by a direct effect of the drug," it's "overwhelmingly more likely that that increased risk of death isn't the drug but because they were sick."

FDA officials, commenting on the new research, said doctors should consider the heart risks of Zithromax and other antibiotics. One cardiologist, Dr. Tara Narula, told MyHealthNews the new data is welcome. "A lot of people got nervous when the FDA came out with their warning," Narula said. The latest study will help doctors sort out the risks for various types of patients, she said.

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