The U.S. Food & Drug Administration (FDA) is reviewing a new study that reported an increased risk of sudden, heart-related deaths among people using the antibiotic Zithromax (azithromycin), known popularly as Z-Pak. In a statement issued late yesterday, the FDA said patients being treated with Zithromax should not stop taking the antibiotic without speaking with their doctor. The agency also advised physicians to be aware that Zithromax and other antibiotics in the same class, called macrolide, have the potential to cause potentially deadly heart arrhythmias.
Zithromax is an antibiotic made by Pfizer Inc. Though Z-Pak tends to be more expensive than amoxicillin and other antibiotics, many doctors and patients prefer Zithromax because it is taken for only five days. According to the FDA, Zithromax is approved to treat:
- Acute bacterial exacerbations of chronic pulmonary disease
- Acute bacterial sinusitis
- Community-acquired pneumonia
- Uncomplicated skin and skin structure infections
- Urethritis and cervicitis
- Genital ulcer disease
According to the FDA, azithromycin belongs to a class of antibacterial drugs called macrolides, which have been associated with cardiovascular effects; specifically, prolongation of the QT interval. Prolongation of the QT interval can lead to torsades de pointes (TdP), an abnormal heart rhythm, which can be fatal. Other antibiotics in this class include clarithromycin (Biaxin) and erythromycin.
According to the agency, 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. The drug labels for clarithromycin and erythromycin also contain information about QT interval prolongation in the “Warnings” section. The FDA says it is s in the process of updating risk information in the drug labels for additional macrolide antibacterial drugs.
NEJM Zithromax Study
On May 17, the New England Journal of Medicine (NEJM) published a study which found that patients taking Zithromax faced an increased risk of death from sudden heart problems compared to people using no antibiotic, or those taking alternative antibiotics. The study analyzed health records and data on millions of prescriptions for several antibiotics given to about 540,000 Tennessee Medicaid patients from 1992 to 2006. The risk of death reported in people taking Zithromax was more than double that of patients on amoxicillin, or those who took none. The highest risks were seen in Zithromax patients with existing heart problems.
In yesterday’s Statement, the FDA pointed out that the NEJM the study only addressed azithromycin, and did not examine any other macrolide antibacterial drugs.