F.D.A. Raises Heart Alert on Antibiotic in Wide Use

The Food and Drug Administration on Tuesday toughened a warning it made last year about the potential risks of azithromycin, a commonly used antibiotic that can cause changes in the electrical activity of the heart that may lead to a fatal irregular heart rhythm in some patients.

The risks, which have been noted in the warning labels on the drug since March 2012, were quantified in greater detail in a study published last spring in the New England Journal of Medicine that was led by a professor of preventive medicine at Vanderbilt University.

Last May, the F.D.A. announced that it would review the study, which found a small increase in the likelihood of death in people treated with a five-day course of azithromycin, compared with people treated with other antibiotics, such as amoxicillin and ciprofloxacin. Two related antibiotics, erythromycin and clarithromycin, were already known to raise the risk of death, but azithromycin had been thought to be safe

The stricter warning on Tuesday was a result of that review, said Stephanie Yao, a spokeswoman for the F.D.A. She said the language on the labels for the drug had been strengthened to include, among other things, details from the 2012 study, and information from a later study by Pfizer.
Patients at risk for developing this condition include the aging, those with histories of heart problems or with low levels of potassium or magnesium in their blood, those with slow heart rates and those taking medication that is known to lengthen the intervals between heartbeats.
Azithromycin is used to treat bacterial infections, including [color=rgb(102, 102, 153)] bronchitis [/color], [color=rgb(102, 102, 153)] pneumonia [/color], sore throats and earaches. It is familiar to many people as the “Z-Pak,” to be taken for five days, and part of its appeal is its convenience; many other antibiotics must be taken for 10 days or longer.
Pfizer, which manufactures Zithromax, a brand name for azithromycin, said in a statement that the potential risk has been “well established in this class of antibiotics,” and that, in collaboration with the F.D.A., it has updated the label on Zithromax, to inform doctors and patients about it.
The company said that the drug, which has been on the market for about 20 years, and is now being produced by other manufacturers in a generic form, “continues to be an effective treatment option for patients all over the globe suffering from many types of bacterial infections.”