The popular antibiotic Zithromax (commonly referred to as a Z-Pak) is prescribed to tame
infections caused by bacteria, like strep throat, according to Pfizer,
the maker of the drug. But the Food and Drug Administration (FDA) says Z-Paks could actually be hazardous to your health.
FDA issued an ominous
warning Tuesday cautioning about a potentially deadly cardiac complication
associated with taking the prescription medicine. The warning follows a study
published in the New England Journal of Medicine that compared the risks of
cardiovascular deaths in patients who took the drug versus those who’ve taken
other antibiotics including amoxicillin. The study says Z-Paks lead to higher
rates of fatal heart rhythms.
The FDA says Z-Paks “can cause abnormal changes in the
electrical activity of the heart that may lead to a potentially fatal irregular
That’s bad news for millions, as Zithromax is a popular
choice of doctors because
patients can take fewer doses over a shorter period than many other
antibiotics. U.S. sales of the drug in 2011 exceeded $450 million, according to
The FDA says “patients at particular risk for developing this condition include those with known risk factors such as existing QT interval prolongation, low blood levels of potassium or magnesium, a slower than normal heart rate, or use of certain drugs used to treat abnormal heart rhythms, or arrhythmias.”
QT interval is a measure of time between the
start of the Q and the end of the T waves that are part of the heart’s
electrical cycle. These waves represent functions performed both the right and
The dangerous heart rhythm known as prolonged QT interval
could indicate the ventricles are not working properly and could be an
indication or a very fast heart rhythm that arises entirely in the lower
chamber of the heart.
There are few symptoms of prolonged QT interval, but they may include a sudden loss of consciousness.
The FDA has updated the
drug's labels with information about the risk of prolonged QT interval and cautions doctors should take care when prescribing the drug to anyone with a
history of heart disease or other heart issues. Pfizer issued an emailed
statement that said most patients will not be affected by this label change and
stressed other antibiotics in the same class have similar risks.
“Patients who are currently prescribed Zithromax should talk
to their doctors or healthcare providers if they have questions regarding their
treatment. Zithromax has had a well-established benefit risk profile for more
than 20 years and continues to be an effective treatment option for patients
all over the globe suffering from many types of bacterial infections,” Pfizer
said in the statement.
Protecting Your Heart
The study suggests there would be 47 extra heart-related deaths per 1 million courses of treatment with Zithromax, compared with another antibiotic, amoxicillin, according to the Associated Press.
As with all medicines, the best way to protect your heart
and overall health when taking Zithromax is with clear communication. Talk to
your doctor about your current health and any possible side effects and drug