Azithromycin is a commonly used antibiotic made by Pfizer, Inc. and sold as Zithromax®. Many people have taken this drug to treat pneumonia, sore throats or ear infections.
In 1999, the Cystic Fibrosis Foundation recognized that azithromycin might help people with cystic fibrosis (CF) who have a positive sputum culture for Pseudomonas aeruginosa(Pseudomonas) and designed a clinical trial to test that possibility.
During the first clinical trial, lung function (FEV1), weight, use of antibiotics, and days spent in the hospital to treat lung infections were watched for changes. The people with CF who were involved in the study were split into two groups. One group took a placebo—an inactive pill that has no treatment value (sometimes called a sugar pill). The other group took azithromycin.
During this trial, neither the patients nor the CF researchers knew which patients took azithromycin or placebo pills. Over six months, the group that took the azithromycin had about a 6 percent improvement in their lung function, fewer pulmonary exacerbations, took fewer antibiotics (other than azithromycin) and had an increase in their weight. They also spent 47 percent fewer days in the hospital for the treatment of a lung infection.
In the second study, the kids with CF did not have Pseudomonas for at least one year, were 6 to 18 years of age, and had mild to moderate lung disease, although most had mild lung disease.
Over six months, the group that took the azithromycin had fewer exacerbations, took fewer oral antibiotics and had an increase in their weight.
Lung function was about the same in those who took placebo and those who took azithromycin. However, the people in the azithromycin group reported less coughing than the group taking the placebo.