Common Antibiotic Linked to Cardiac Deaths

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Common antibiotic linked to cardiac deaths

Associated Press

Sept. 8, 2004, 4:57PM

 

http://www.chron.com/cs/CDA/ssistory.mpl/front/2785029

 

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 huge 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 new 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.

 

Taken alone, erythromycin doubled the very low risk of sudden cardiac

death among patients in the study.

 

In patients taking other drugs -- those that increase erythromycin's

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 electrocardiology

laboratory at University of Medicine and Dentistry of New Jersey in

Newark. " It was thought that erythromycin is a generally safe drug. "

 

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. However, family doctors are

less likely to know about it, Saric said.

 

This study, in Thursday'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 seems to come from other drugs slowing the

breakdown of erythromycin, which increases its concentration. At high

levels it traps salt inside resting heart muscle cells, prolonging

the time until the next heartbeat starts, and sometimes triggering an

abnormal, potentially fatal, rhythm.

 

The findings show doctors should choose an alternative antibiotic,

Ray said, at least when prescribing the drugs that interact.

Amoxicillin, another popular antibiotic, showed no cardiac risk.

 

" There are other antibiotics that provide the same antimicrobial

activity without building up in the blood the way erythromycin does, "

Ray said.

 

Ray's team of doctors and nurses spent years studying detailed

medical records of 4,404 Medicaid patients from Tennessee who

apparently died of cardiac arrest from 1988-93. The team confirmed

1,476 cases of cardiac arrest, then studied Medicaid's records of

each patient's medication use.

 

Only a small number of patients had taken both erythromycin and any

of the antibiotics or heart drugs carrying a risk.

 

Still, three of them died. Statistically, it was extremely unlikely

those deaths were due to chance, according to Ray and other experts.

 

The deaths were in patients taking verapamil or diltiazem, both blood

pressure drugs sold as generics and also under various brand names:

Verelan and Isoptin for verapamil, Cardizem and Tiazac for diltiazem.

 

 

Other drugs posing a risk with erythromycin, Ray said, include the

antibiotic clarithromycin, sold under the Biaxin brand; fluconazole,

or Diflucan, for vaginal yeast infections; and the antifungal drugs

ketoconazole (Nizoral) and itraconazole (Sporanox). Pills and

injections of the drugs, but not topical forms, carry the risk.

 

" People may be taking these medications for years, and they develop a

throat infection and someone gives them erythromycin, and that's it, "

Saric said.

 

The AIDS drugs called protease inhibitors and grapefruit juice also

should be avoided, Ray said, because they, too, can boost blood

levels of erythromycin.

 

Erythromycin, in turn, boosts blood levels of verapamil and

diltiazem, which slow heart rate, and thus can worsen abnormal

rhythms, said American Heart Association spokeswoman Dr. Nieca

Goldberg. The findings show why people should keep a list of

medications they take and share them with all their doctors, said

Goldberg, chief of women's cardiac care at Lenox Hill Hospital in New

York City.

 

About 340,000 Americans die each year of cardiac arrest, also called

sudden cardiac death, according to the heart association. The

condition is caused by abnormal heart rhythm, usually when the heart

begins beating too rapidly or too chaotically to efficiently pump

blood.

 

Goldberg noted the once-blockbuster nonsedating allergy drug Seldane

was taken off the market, in 1998, after reports linking it to sudden

cardiac death due to the same types of abnormal heart rhythms.

 

The study was funded by the Food and Drug Administration, two other

federal health agencies and the drug company Janssen Pharmaceutica,

which makes Nizoral and Sporanox. Ray and two other researchers have

received consulting fees from other pharmaceutical or health products

companies.

 

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