Azithromycin is an antibiotic used to treat a wide variety of infections and considered by the World Health Organization to be an essential medicine. Azithromycin is a generic medication, sold under many names, including Zithromax. First discovered in 1980 by a Croatian pharmaceutical company, Pfizer bought the rights to sell the drug as Zithromax in the U.S. It has since lost exclusive rights and no azithromycin is available from more than one company.
Zithromax may be an essential medicine, and it can treat a number of infections with fewer doses than other antibiotics, but it also may cause serious side effects. One of the most problematic of these did not come to light until 2013 when the U.S. Food and Drug Administration (FDA) issued a warning about the potential for Zithromax to increase the risk of fatal heart disease.
What is Zithromax?
Azithromycin was discovered by Croatian researchers at a pharmaceutical company called Pilva. A team of researchers at the company made the discovery of the compound with its antibacterial effects in 1980. By 1986, Pilva had signed a licensing agreement with Pfizer to market the drug exclusively in the U.S. and in Western Europe.
Pfizer brought out its new antibiotic in 1992 and called it Zithromax. Zithromax came in a packet of five tablets, called a Z-Pak, and a course of treatment required just one tablet per day for five days, about half the number of doses of other antibiotics on the market. The FDA approved Zithromax initially in 1992 for the treatment of skin and respiratory infections, but over the years that approval has been updated to include a number of other infections. In addition to the Z-Pak, Zithromax can be taken as a liquid or an extended release liquid.
Uses for Zithromax
Originally the FDA approved azithromycin for the treatment of acute bronchitis and sinusitis in adults as well as uncomplicated skin infections in adults. Later it was approved for the treatment of other infections, including urethritis, cervicitis, genital ulcer disease, pneumonia, pharyngitis, and tonsillitis in adults. Zithromax can also be used to treat middle ear infections, pneumonia, tonsillitis, and pharyngitis in children.
Azithromycin is not indicated for use in people with pneumonia who have certain risk factors that make oral antibiotic treatment inappropriate. The labeling for Zithromax also warns that it should only be used to treat those infections that are caused by a bacteria type susceptible to this type of antibiotic. Overuse of antibiotics on those bacteria that are not susceptible leads to the development of bacteria that are resistant to drugs.
Off-label, a doctor may prescribe azithromycin to treat other infections, like traveler’s diarrhea, Legionnaires’ disease, whooping cough, babesiosis, an infection carried by ticks, and certain sexually transmitted diseases, like gonorrhea and chlamydia. It may also be used to prevent infections in people having medical procedures or in victims of sexual assault.
How it Works
Azithromycin belongs to a class of drugs called macrolide antibiotics. It works as an antibiotic by preventing bacterial cells from growing. It accomplishes this by interfering with the synthesis of proteins within the cells. Proteins are essential for the bacteria to grow. Without them, the cells will simply die or be killed by the patient’s immune system.
The most common side effects of Zithromax are gastrointestinal. It may cause nausea, diarrhea, vomiting, or stomach cramping and abdominal pain. Headaches, nervousness, and skin reactions are also possible. Uncommon, but also possible with Zithromax are jaundice, or a yellowing of the skin or eyes, dizziness, fatigue, chest pains, and heart palpitations. Approximately 12 percent of people taking a course of this antibiotic will experience some type of side effect. Most people tolerate it well.
Of the rare, but serious possible complications of taking Zithromax, liver toxicity can be severe. The labeling and prescribing information for the drug warns that any patient experiencing symptoms of hepatitis, inflammation of the liver, should discontinue use and see a doctor immediately. Liver toxicity caused by azithromycin has the potential to be severe and fatal incidents have been reported. Signs of hepatitis include fatigue, darkened urine, abdominal pains, muscle aches, jaundice, and a loss of appetite.
Also reported occasionally with use of Zithromax is anaphylaxis. It is rare, but serious and potentially deadly. Anaphylaxis is an extreme allergic reaction. It requires emergency medical attention and if not treated immediately, will cause death. Signs of this severe reaction include skin rashes and itchy skin, swelling in the face, mouth, or throat, difficulty swallowing, wheezing, and difficulty breathing.
Zithromax may also increase the risk of heart problems and resulting death in patients, a risk which was only uncovered in a study published in 2012, about two decades after the antibiotic was first put on the market. The study was published in the New England Journal of Medicine and it found that people taking azithromycin were more likely to die of cardiovascular events than people taking another type of antibiotic or no antibiotic.
From reports of adverse events sent to the FDA the researchers were able to figure out that Zithromax use led to irregular heartbeats. In patients with an existing risk for death by a cardiovascular event, this irregularity increased the risk, and in some cases, led to death. Patients at risk included those with low potassium or magnesium levels in the blood, with arrhythmias, with a slower heartbeat, and with a QT interval prolongation, a type of irregular heartbeat.
Because of the published evidence, the FDA issued a warning in 2012. The warning outlined the findings of the study. The study’s results also led to Pfizer conducting further research into the cardiovascular risks of Zithromax. The results from the Pfizer study confirmed the risk, and the FDA issued a stronger warning in 2013. This warning stated that azithromycin products have the potential to cause changes to the electrical activity of the heart, which could cause an irregular heartbeat that could be fatal in some patients.
Pfizer updated its Zithromax labeling to include all the most recent information and warnings about the risk of irregular heart rhythms and the resulting risk of death for some patients. The company did this in response to the irrefutable evidence from researchers and the announcements and warnings from the FDA. Although they responded to the evidence uncovered by research, it was a full two decades between when the drug was first made available to when the company communicated to the public that there was this fatal risk associated with it.
Because of this long gap between years of use of the medication and public awareness of the risks, Zithromax users may have reason to sue Pfizer. The loved ones of those who died of a cardiovascular event while taking the antibiotic may have the strongest cases. They may be able to make the case that Pfizer knew or should have known that this risk existed. If researchers were able to find the risk by searching the FDA’s database of reported adverse events, Pfizer should have been able to do the same. If you have suffered because of Zithromax, talk to a lawyer about the options you have for taking action and seeking monetary compensation.