Zithromax: safety or security threat?

Anyone who has ever visited a doctor’s office is likely to have taken a course of azithromycin, an antibiotic also commonly known as Zithromax or Z-Pak. Azithromycin belongs to a group of antibiotics called macrolides and is used to treat respiratory, throat, ear and other infections.

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According to a 2011 IMX Health report, approximately 40 million people in the outpatient setting received azithromycin prescriptions that year, making it the most prescribed antibiotic, and some could even be prescribed in the United States. This phenomenon was due in part to the popularity of drugs among patients for their clever packaging, convenient 5-day course and catchy name.

Security threat

Carefree days of azithromycin prescription stopped abruptly in 2012, when an observational study, published in the New England Journal of Medicine (NEJM) (1), concluded that people who took the antibiotic had a higher incidence of sudden cardiac death, compared to people who took other antibiotics or did not take anything. Adverse events only occurred during the course of 5 days treatment, suggesting that the risk dissipated as the drug removed from the body in the subsequent days.

Prior to that, the FDA had been monitoring post-marketing surveillance which suggested that macrolide antibiotics were associated with QT prolongation, a change in heart rate that could potentially lead to a life-threatening condition called torsades of pointes. Following NEJM 2012, the FDA issued a safety report for the public and led the manufacturer to include a warning label for prescribers. The new label warned physicians about the potential for adverse events in those with known QT interval prolongation, electrolyte disturbances or known heart conditions.

…or not.

But a new study is now refuting the findings of the 2012 report. The article in the Journal of the Canadian Medical Association (CMAJ) states the safety of macrolide antibiotics and claims that the FDA’s warning, The 2012 study, may have been “exaggerated.”

How could they come to a different conclusion? The February 2016 research was a population-based study to determine whether macrolides (azithromycin, also clarithromycin or erythromycin) caused major incidences of death due to irregular heart rhythms in older people compared to the antibiotics amoxicillin, cefuroxime and levofloxacin.

What is the difference?

To obtain answers, the authors reviewed health records of 503 612 individuals aged 65 years or older who were prescribed a macrolide or a non-macroline antibiotic between April 2002 and March 2013. They sought death incidents from ventricular arrhythmia, Cause mortality within 30 days of being prescribed one of the study antibiotics. The result was conclusive: macrolide antibiotics, compared to non-macrolide antibiotics, did not cause further deaths due to irregular heart rhythms (0.03% vs. 0.03%). In fact, macrolides were associated with a lower risk of all-cause mortality (0.62% vs. 0.76).

The result of this new study alleviates some of the safety concerns surrounding the use of azithromycin – and other macrolides – particularly in older individuals, who are more likely to have increased cardiovascular risk. The authors also cited the findings of four other studies, published in peer-reviewed medical journals between 2012 and 2014, which showed that macrolides do not categorically increase the risk of cardiovascular death and overall mortality.

So, a health scare or a health threat?

The message to take home is that azithromycin is a valuable life-saving antibiotic, but as with anything there can be some risk. So if you are in the risk group, keep an eye on things. We need more antibiotics, not less, so this finding on azithromycin is a victory for the public.