FDA: Zithromax May Lead to Potentially Fatal Heart Rhythms

The U.S. Food & Drug Administration is warning the public that Zithromax (azithromycin), also known as Zmax can cause abnormal changes in the electrical activity of the heart. This may lead to a potentially fatal irregular heart rhythm.

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 who use certain drugs for treatment of abnormal heart rhythms or arrhythmias. The FDA’s Drug Safety Communication followed a review of a study conducted by medical researchers and another study by a manufacturer of the drug that assessed the potential for Zithromax to cause abnormal changes in the electrical activity of the heart.

In a previously released statement dated May 17, 2012, the FDA discussed a study comparing the risks of cardiovascular death in patients treated with the antibacterial drugs azithromycin, amoxicillin, Cipro (ciprofloxacin), and Levaquin (levofloxacin), or no antibacterial drug. The study reported an increase in cardiovascular deaths, and in the risk of death from any cause, in persons treated with a five-day Zithromax course when compared to persons treated with amoxicillin, Cipro, or no drug. The risks of cardiovascular death associated with Levaquin treatment were similar to those associated with Zithromax treatment.

A change to the FDA-approved indications for Zithromax include: Acute bacterial exacerbations of chronic obstructive pulmonary disease (COPD); acute bacterial sinusitis; community-acquired pneumonia; pharyngitis/tonsillitis; uncomplicated skin and skin structure infections; urethritis and cervicitis, genital ulcer disease,

The FDA recommends that health care professionals take into account the risk of torsades de pointes and fatal heart rhythms with Zithromax when considering treatment options for patients at risk for cardiovascular events. The FDA also notes that the potential risk of QT prolongation when taking Zithromax should appropriately considered when choosing an antibacterial drug.

Last year, we wrote that Pfizer Inc. was hit with a warning letter from federal health regulators over a brochure the company used to promote its Zithromax antibiotic. According to the June 19, 2012 FDA warning letter, the Zithromax brochure was deemed false and misleading because it: Omitted and minimized important Zithromax risk information, including its association with heart rhythm problems; made unsubstantiated superiority claims; omitted material facts; broadened the indication for Zithromax; made misleading efficacy claims; and made unsubstantiated claims.

In May 2012, The New England Journal of Medicine (NEJM) published a study that found that patients taking Zithromax faced a doubled risk of death from sudden heart problems compared to people using no antibiotic, or those taking alternative antibiotics. The highest risks were seen in Zithromax patients with existing heart problems.

Alternative drugs in the macrolide class of medications, or non-macrolides drugs such as the fluoroquinolones, also have the potential for QT prolongation or other significant side effects that should be considered when choosing an antibacterial drug.

As we’ve explained, fluoroquinolones—antibiotics such as Cipro, Levaquin, and Avelox (moxifloxacin)—have long been linked to dangerous side effects such as increased risks of suffering acute kidney failure. We’ve also written that Avelox and Levaquin have been linked to liver injury in the elderly and that fluoroquinolone antibiotics are also associated with severe tendon injuries, including tendon rupture and tendonitis. Fluoroquinolone use may result in other rare but severe and even life-threatening side effects that involve swelling of the throat and/or face, difficulty swallowing, shortness of breath, rapid heartbeat, tingling in the toes or fingers, hives or itching, and loss of consciousness.

We also wrote that fluoroquinolone antibiotics have been linked to detached retinal problems. Retinal detachment can lead to permanent blindness if not surgically treated within a few days of onset. Health Canada also previously warned that people with myasthenia gravis should avoid fluoroquinolone antibiotics because they could worsen the rare, chronic disease that causes progressive muscle weakness, including in the eye and face muscles, neck and throat muscles, and limb muscles. Another recent study found that Zithromax may increase risks for death, specifically in patients with heart disease. The increasing use of potent drugs such as Cipro, Levaquin, and Avelox, has also been linked to serious antibiotic resistant infections including antibiotic-resistant Staphylococcus aureus (MRSA) and Clostridium difficile. In fact, one study blamed fluoroquinolones for 55 percent of C. difficile infections at one Quebec hospital.