The widely used antibiotic azithromycin does not increase the risk of an abnormal heart rhythm, according to a new study.
Azithromycin (Zithromax) is often used to treat respiratory and urinary tract infections. It belongs to a class of drugs known as macrolides. Another type of macrolide called erythromycin may disrupt the normal heart rhythm. That antibiotic has been linked to a life-threatening heart condition called ventricular arrhythmia.
Recent studies have reached conflicting conclusions about whether azithromycin is also associated with an increased risk of death from this condition.
In an effort to clarify the issue, researchers analyzed data from more than 14 million new users of antibiotics. The patients were in Denmark, Germany, Italy, the Netherlands and the United Kingdom.
The study found that 0.1 percent developed ventricular arrhythmia. Only 30 of these patients were new users of Azithromycin (Zithromax) .
People taking azithromycin were no more likely to develop ventricular arrhythmia than those who took another widely used antibiotic called amoxicillin. Amoxicillin is a penicillin drug. However, those taking azithromycin were at greater risk than those who did not take antibiotics, the study found.
The results of the study were published on April 18 at the Canadian Medical Association Journal (CMAJ).
“This finding suggests that the risk of ventricular arrhythmia is more likely to be due to poor health of a person and caused by their infection, rather than to azithromycin itself,” said study author Dr. Gianluca Trifiro of The University of Messina in Italy In a press release from the magazine.
The researchers said their data came from people who were not hospitalized. This means that their findings may not apply to the use of azithromycin in hospitals, where patient health and antibiotic use is very different.