Study finds Zithromax (azithromycin) may carry higher risk of death than other antibiotics

People taking the popular antibiotic Zithromax (azithromycin), commonly called the “Z-pack,” may have more than double the risk of death from cardiovascular problems than people taking other antibiotics.

Vanderbilt University researchers found in a new study that patients taking a five-day treatment with azithromycin had 2.5 times the risk of death by cardiac arrhythmia than people taking other antibiotics or no antibiotics at all.

“We believe this study adds important information on the risk profile for azithromycin,” study author Wayne A. Ray, Ph.D., professor of Preventive Medicine at Vanderbilt University, told Reporter. “For patients with elevated cardiovascular risk and infections for which there are alternative antibiotics, the cardiovascular effects of azithromycin may be an important clinical consideration.”

The researchers analyzed patient data in Tennessee’s Medicaid program (TennCare) from 1992-2006. They excluded patients with serious non-cardiovascular illness and those recently released from a hospital. The study included records for 347,795 prescriptions for azithromycin, 1,348,672 amoxicillin prescriptions, 264,626 ciprofloxacin prescriptions, 193,906 levofloxacin (Levaquin) prescriptions and 1,391,180 controls who took no antibiotics.

Results showed patients taking amoxicillin had no increased rates of death compared to patients who took no antibiotics. Death while using azithromycin was 2.5-fold higher than with amoxicillin or no antibiotic use. The risk of death was also significantly greater with azithromycin than with ciprofloxacin but did not differ significantly from that with levofloxacin, which is already associated with increased risk of sudden cardiac death.

Death during azithromycin treatment was most evident in patients who had a high baseline risk of cardiovascular disease, showing the drug may be more likely to cause abnormal heart rhythms in people with a history of heart attack or heart failure, diabetes, bypass surgery or stents.

The study Azithromycin and the Risk of Cardiovascular Death appears in the May 17, 2012 issue of The New England Journal of Medicine. The National Heart, Lung, and Blood Institute and Agency for Healthcare Quality and Research Centers for Education and Research on Therapeutics funded the study.

In response to the study, the U.S. Food and Drug Administration released a statement regarding azithromycin and the risk of cardiovascular death.

“Patients taking azithromycin should not stop taking their medicine without talking to their healthcare professional,” the FDA advised. “Healthcare professionals should be aware of the potential for QT interval prolongation and heart arrhythmias when prescribing or administering antibacterial drugs.”

Azithromycin is in a class of drugs called macrolides. Other drugs in this class, such as and erythromycin and clarithromycin, were already known to cause abnormal heart rhythms and carry an increased risk of death. Another study authored by Ray and published in the September 9, 2004 issue of The New England Journal of Medicine found patients taking erythromycin had twice the risk of sudden death from cardiac causes than amoxicillin users.

FDA-approved indications for azithromycin include:

• Acute bacterial exacerbations of chronic pulmonary disease
• Acute bacterial sinusitis
• Community-acquired pneumonia
• Pharyngitis/tonsillitis
• Uncomplicated skin and skin structure infections
• Urethritis and cervicitis
• Genital ulcer disease

According to The New York Times, doctors wrote more than 55.3 million prescriptions for azithromycin in the United States last year.