Study Questions Link Between Zithromax and Heart-Related Deaths

Researchers from Public Health — Seattle are raising questions about the possible links between the antibiotic Zithromax and heart problems seen in recent research, indicating that they have failed to find any correlation. 

In a Letter to the Editor published in the New England Journal of Medicine on May 15, several researchers indicate that they question whether there is a connection between side effects Zithromax and an increased risk of cardiovascular death. They also note that if such a link exists, the risks are far smaller than those associated with gonorrhea, which Zithromax is frequently used to treat.

The report contradicts the findings of FDA investigators, which issued a Zithromax drug safety communication in March 2013, warning that the antibiotic can cause serious and potentially fatal abnormal heart activity.

The FDA indicated that Zithromax, which is also commonly known as Z-Pak or Zmax, can disrupt the electrical activity of the heart. The agency’s conclusions came after an investigation into the risk of Zithromax heart problems that was started in May 2012, examining data from a number of studies.

Zithromax (azithromycin) is a member of a class of antibacterial drugs known as macrolides, which have been known to cause abnormal heart rhythm problems, including QT interval prolongation. These side effects can lead to a fatal heart condition, known as torsades de pointes.

In May 2012, a study published in the New England Journal of Medicine first warned about the potential heart risks. Researchers found patients were 2.5 times more likely to die due to heart related problems on a five day Zithromax treatment when they compared it to treatment with other antibiotics or no antibiotic therapy.

In this latest study, researchers looked at data on 260,048 patients who were diagnosed with either gonorrhea, chlamydia, or both from 1993 to 2012 from the Oregon Public Health Division and Public Health — Seattle and King County. About 62%, 162,385 patients, received Zithromax. The rest received other antibiotics, primarily tetracycline.

According to the researchers’ findings, which looked for deaths among patients within 10 days after treatment, there were no deaths from cardiovascular causes among patients treated with either Zithromax or any other antibiotic during that entire time period. The only deaths they found within the 10-day period were two suicides, one murder, one drug overdose and one case of rectal cancer.

Researchers note that one major study linking Zithromax to heart problems was conducted among older patients that did not reflect the typical population treated for sexually-transmitted infections. Even that study only found one death out of 144,165 persons, the researchers said.

“Our findings should be reassuring to health care providers who prescribe azithromycin to treat gonorrhea and chlamydia, and they support the conclusion of the (U.S. Centers for Disease Control and Prevention) that research related to possible cardiac toxicity associated with azithromycin should not lead to a change in current treatment guidelines for STDs,” the researchers concluded.