Azithromycin is one of the most widely used antibiotics in the United States. In 2011 more than 40 million Americans received a prescription for azithromycin (Zithromax; Z-pak; Zmax). Recently, the Food and Drug Administration distributed a drug safety announcement regarding the risk of azithromycin in causing fatal heart arrhythmias (irregular heart beat). Should we now stop using azithromycin?
Here's how this drug safety warning came about. Last year researchers reviewed the electronic records of Medicaid patients in Tennessee. They found that persons receiving a short course of azithromycin were more likely to suffer death from cardiovascular disease, especially sudden death thought due to heart arrhythmia, than persons not receiving antibiotics or receiving an alternative antibiotic, amoxicillin. If you were a person with no special risk for cardiovascular disease, then the increased risk of dying while taking azithromycin was approximately 1 in 111,000. If you had serious underlying cardiovascular disease or a tendency to develop heart irregularity, the excess risk of dying while taking azithromycin was 1 in 4,000. To put this in perspective, your risk of dying from a bolt of lightning is estimated at 1 in 84,000, and your risk of dying in an automobile accident is estimated at 1 in 100.There are two classes of antibiotics that are known to predispose to irregular heart rhythms. These are the family of antibiotics called macrolides (including azithromycin, clarithromycin [Biaxin], and erythromycin) and fluoroquinolones (including ciprofloxacin [Cipro], levofloxacin [Levaquin], and moxifloxacin [Avelox]). The study cited above found that the risk of cardiovascular death when taking levofloxacin was the same as when taking azithromycin. It also found that the risk of death from cardiovascular disease did not persist after the course of antibiotic.
Our take on this evidence?
1. The evidence suggesting that azithromycin can stimulate fatal heart arrhythmias is compelling and believable.
2. Will we continue to prescribe azithromycin for our otherwise healthy patients and family members for bacterial respiratory tract infections? Yes. Antibiotics remain among the relatively few drugs in our medical toolbox that can cure disease.
3. People who should avoid azithromycin (and other macrolide antibiotics) and levofloxacin (and other fluoroquinolone antibiotics) are those with a known tendency to a particular type of irregular heart rhythm of the ventricle (ventricular arrhythmia) caused by slow electrical repolarization of the heart muscle, manifesting as prolongation of the QT interval on electrocardiogram. Your doctor will know if you have “prolonged QT syndrome” or are taking other medications that might cause a prolonged QT interval, especially heart medicines such as dofetilide, amiodarone, or sotalol. A very low blood level of potassium or an abnormally slow heart rate might also put you at risk for this type of heart arrhythmia.
4. Is this evidence one more reason that otherwise healthy people with viral head and chest colds should take symptomatic treatment (such as acetaminophen [Tylenol], chicken soup, and tea with honey) rather than unnecessary and unhelpful antibiotics? Definitely yes.