The Food and Drug Administration issued tougher warnings about azithromycin risks March 12, following a review of a 2012 study in the New England Journal of Medicine that found a slight increase in cardiovascular death among patients prescribed the common antibiotic. The new FDA warning advises of possible changes to the heart’s electrical activity that could lead to fatal irregular heart beat in some patients.
“Patients at particular risk for developing this condition include those with known risk factors such as existing QT interval prolongation, low blood levels of potassium or magnesium, a slower-than-normal heart rate, or use of certain drugs used to treat abnormal heart rhythms or arrhythmias,” the FDA said in a drug safety communication. “FDA has issued a (warning) as a result of our review of a study by medical researchers, as well as another study by a manufacturer of the drug, that assessed the potential for azithromycin to cause abnormal changes in the electrical activity of the heart.”
But patients outside of the affected class need not panic about cardiovascular side effects. The increased risk identified in the study were tiny, as in 47 deaths for every 1 million patients who took azithromycin tiny. That breaks down to one death for every 21,276 courses. It would take 291 years to take that many courses of the drug if taken continuously.
Of course the risk is slightly higher for patients in at-risk categories such as the aged and those already diagnosed with heart rhythm abnormalities and heart disease. The study found one additional death for every 4,100 courses of azithromycin prescribed to patients in the highest-risk categories. But that also mean there was really only one extra death for every 110,000 courses taken by low-risk patients.
Azithromycin, or more commonly known as “Z-Pak,” is often prescribed as a five-day regimen to treat bacterial infections such as bronchitis, pneumonia, sore throats and ear infections. Because of its convenience, patients often request a Z-pack for ailments such as a cold that antibiotics are unlikely to help. Overuse of azithromycin can lead to antibiotic resistance, and is a much greater danger to patients than the tiny risk of fatal heart abnormalities.
Pfizer, one of the major manufacturers of azithromycin, says the potential risks of the antibiotics have been “well established” and that it has updated the label on Zithromax, in accordance with the FDA, to inform doctors and patients. According to the company, the drug has been on the market for 20 years and “continues to be an effective treatment option for patients all over the globe suffering from many types of bacterial infections.”