The FDA is notifying healthcare professionals of a new study reporting a small increase in cardiovascular death, and in the risk of death from any cause, in patients treated with a 5-day course of azithromycin (Zithromax; Pfizer) compared to persons treated with amoxicillin, ciprofloxacin, or no drug.  FDA is reviewing the results from this study and will communicate any new information on azithromycin and this study or the potential risk of QT interval prolongation after the agency has completed its review.

Azithromycin belongs to a class of antibacterial drugs called macrolides, which have been associated with cardiovascular effects; specifically, prolongation of the QT interval. In 2011, FDA reviewed macrolide drug labeling information related to QT interval prolongation and torsades de pointes. The Warnings and Precautions section of the Zmax drug label (azithromycin extended-release for oral suspension) was revised in March 2012 to include new information regarding risk for QT interval prolongation, which appears to be low. The drug labels for clarithromycin and erythromycin also contain information about QT interval prolongation in the Warnings section. FDA is in the process of updating risk information in the drug labels for additional macrolide antibacterial drugs. Healthcare professionals should be aware of the potential for QT interval prolongation and heart arrhythmias when prescribing or administering macrolides.

Zithromax is indicated for mild to moderate susceptible infections including acute bacterial exacerbations of COPD, acute bacterial sinusitis, acute otitis media, community-acquired pneumonia, pharyngitis/tonsillitis, uncomplicated skin and skin structure infections, urethritis, cervicitis, chancroid in men, and Mycobacterium avium complex (MAC) disease.

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