Anantibiotic frequently used to treat pneumonia and bronchitis is linked to ahigher risk of sudden death in adults, particularly those with heartconditions, a new study reveals. 

Azithromycin,which is frequently referred to as a “Z-Pak,” was generally believed to besafer than antibiotics such as erythromycin and clarithromycin. Previous studies have linked erythromycinwith a higher risk for heart attack. 

However,when researchers from Vanderbilt University calculated the rate of deaths permillion courses of treatment, based on the medical records of about 540,000 Medicaidrecipients, azithromycin had 64.6 deaths per million courses. Amoxicillin was muchlower, with a rate of 21.8, according to the study.

Individualswith conditions such as heart failure, or who have undergone a bypass, areconsidered to be at a higher risk for death, the New York Times reported. 

Thestudy was published May 17 in the New England Journal ofMedicine.