Zithromax Heart Risks Questioned by New Study

The increased risk of suffering heart problems from Zithromax, a popular antibiotic more commonly known as Z-Pak or ZMax, may be limited to individuals with certain risk factors, according to the findings of new research.  

In a study published this week in the New England Journal of Medicine, Danish researchers found there was no increased risk of cardiovascular events from Zithromax among patients in the general population.

Although recent studies have suggested side effects of Zithromax may increase the risk of serious and potentially life-threatening abnormal heart activity, researchers indicate that the results may be caused by the very infections that Zithromax and other antibiotics were designed to fight.

Researchers found that patients who used Zithromax were at no more of an increased risk of death from cardiovascular problems than patients who took other antibiotics. However, all antibiotic patients had a significantly increased risk of heart problems, which researchers said pointed to the infections the drugs were fighting.

A review of Zithromax by the FDA came up with very different results. In March, the agency issued a warning that its own investigation revealed that the Zithromax, Z-Pak, Zmax and generic azithromycin can cause abnormal heart activity that could be deadly. According to the federal health regulators, which has been investigating Zithromax side effects since May 2012, patients with existing heart rhythm conditions were more vulnerable to Zithromax side effects.

Zithromax (azithromycin) is a member of a class of antibacterial drugs known as macrolides, which have been known to cause abnormal heart rhythm problems, including QT interval prolongation. These side effects can lead to a fatal heart condition, known as torsades de pointes.

In May 2012, a study published in the New England Journal of Medicine first warned about the potential heart risks. Researchers found patients were 2.5 times more likely to die due to heart related problems on a five day Zithromax treatment when they compared it to treatment with other antibiotics or no antibiotic therapy.

Zithromax sales brought in more than $450 million for Pfizer in 2011. It is used to treat respiratory system and urinary tract infections, tonsillitis and other bacterial infections. It is also available as a generic.