Vanderbilt researchers have discovered a rare, but
important risk posed by the antibiotic azithromycin, commonly called a
"Z-pack."
The study found a
2.5-fold higher risk of death from cardiovascular death in the first five days
of taking azithromycin when compared with another common antibiotic or no
antibiotics at all.
Wayne A. Ray, Ph.D.,
professor of Preventive Medicine, and C. Michael Stein, M.B.Ch.B., the Dan May
Chair in Medicine and professor of Pharmacology, collaborated on the research
published in the May 17 edition of the New
England Journal of Medicine.
Azithromycin, commonly
called a "Z-pack" is one of the most popular treatments for bacterial sinus infections and
bronchitis. Although it was previously considered to carry little to no cardiac risk, the
researchers noted well-documented reports in the published literature as FDA
database reports linking azithromycin with serious arrhythmias. Based on this
evidence, the Vanderbilt researchers sought to examine cardiovascular deaths in
patients who were taking the antibiotic.
Tennessee Medicaid
(TennCare) patient records were examined from 1992 to 2006.
The researchers took many
steps in this large, observational, population-based study to rule out other
reasons for the increase in cardiovascular deaths in patients taking
azithromycin.
About 348,000 recorded
prescriptions of azithromycin were compared with millions of similar records
from people who were not treated with antibiotics or were treated with other
antibiotics. The primary comparison was with amoxicillin, an antibiotic that is
considered to be heart safe and is used in similar clinical circumstances as
azithromycin.
While the absolute number
of deaths was quite low, relative to amoxicillin, there were about 47 more
deaths per million courses of therapy in those taking the azithromycin. That
risk increased to 245 additional cardiovascular deaths per million in patients
already known to have a high risk for heart problems.
The researchers
emphasized that the decision to prescribe any antibiotic requires careful
balancing of both potential benefits and risks. This calculation must consider
the severity of the infection, the susceptibility of the organism, the
availability of alternative antibiotics and adverse effects.
"We believe this
study adds important information on the risk profile for azithromycin,"
said Ray. "For patients with elevated cardiovascular risk and infections
for which there are alternative antibiotics, the cardiovascular effects of
azithromycin may be an important clinical consideration."
Journal reference: New
England Journal of Medicine
Provided by Vanderbilt
University Medical Center
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