Study Links Antibiotic to Higher Risk of Heart Attack

A widely used antibiotic long considered safe dramatically increases the risk of cardiac arrest, particularly when taken with some popular drugs for infections and high blood pressure, a study found.

The drug is erythromycin, which has been on the market for 50 years and is prescribed for everything from strep throat to syphilis.

The study shows the need for continuing research on the safety of older medicines, including how they interact with newer drugs, said researcher Wayne A. Ray, a professor of preventive medicine at Vanderbilt University School of Medicine in Nashville.

In patients taking erythromycin along with other drugs that increase its concentration in the blood, the risk of cardiac death was more than five times greater, Ray and his colleagues found. That translates to six deaths for every 10,000 people taking erythromycin for the typical two weeks while on the other drugs.

“This is an unacceptably high risk,” Ray said.

Nobody realized the magnitude of the problem before, said Dr. Muhamed Saric, a cardiologist and director of the electro-cardiology laboratory at the University of Medicine and Dentistry of New Jersey in Newark.

Most heart doctors knew erythromycin alone carried a slight risk because of some individual reports on patient deaths, mostly in people who took the drug intravenously.

The study, in today’s New England Journal of Medicine, was the first to systematically document the risk. It focused on much more commonly used erythromycin pills -- usually sold as a generic -- along with certain medicines for infections and calcium channel blockers for high blood pressure.

Ray said the danger seemed to come from other drugs slowing the breakdown of erythromycin, which increased its concentration.

The findings show doctors should choose an alternative antibiotic, Ray said. Amoxicillin showed no cardiac risk.