Asthma prevalence has steadily increased in the United States since the early 1980s; currently, more than 20 million people are diagnosed with asthma. Individuals with this disease may experience periodic attacks of wheezing, shortness of breath, chest tightness, and coughing. While there are many known causes of asthma, including tobacco smoke and other allergens, the exact cause of some asthma cases remains unknown. Research has shown that in some individuals, respiratory airway infections may play a role in the onset and severity of the disease. Inhaled corticosteroids are commonly used to treat asthma; however, they do not effectively control symptoms for everyone. Clarithromycin, an antibiotic medication used to treat bacterial infections, may be an effective asthma treatment for individuals who do not respond well to inhaled corticosteroids. The purpose of this study is to evaluate the effectiveness of clarithromycin at reducing asthma symptoms.~This study will begin with a 4-week run-in period to standardize participants' asthma medication usage. During this time, all participants will stop their current asthma medications and instead will receive inhaled fluticasone twice a day. Albuterol will be available as a rescue medication if necessary. Study visits will take place every 2 weeks. Blood and saliva samples will be obtained for laboratory tests and participants will complete standardized questionnaires to assess asthma symptoms and quality of life. Spirometry will be performed to measure lung function. Medication adherence will be monitored with a daily diary and an electronic pill counting device. At the end of Week 4, participants will be evaluated for study eligibility. If eligible, participants will undergo a bronchoscopy and a lung biopsy to test for Mycoplasma pneumoniae and Chlamydia pneumoniae, two bacteria that have been identified as possible factors in the development of asthma.~The treatment phase of the study will last 16 weeks. Participants will be randomly assigned to receive either 500 mg of clarithromycin or placebo twice a day, plus inhaled fluticasone. At monthly study visits, spirometry and blood collection will be performed. Standardized questionnaires to assess asthma symptoms will be completed every 2 weeks. Medical adherence will continue to be monitored. At the end of Week 16, participants will stop receiving clarithromycin or placebo, but will continue to receive fluticasone. Asthma symptoms, rescue medication usage, quality of life, and lung capacity will be assessed; tissue samples will be examined for the presence of Mycoplasma pneumoniae and Chlamydia pneumoniae. An 8-week washout period will follow to observe any lingering medication effects and to monitor for safety. Monthly study visits during this period will include spirometry and blood collection.
Asthma can be caused by a variety of factors, including tobacco smoke, allergens, and respiratory airway infections. Many people use inhaled corticosteroid medications to treat their symptoms. These medications, however, are not effective for everyone. Clarithromycin is an antibiotic that may effectively treat asthma in these individuals. This study will evaluate the effectiveness of clarithromycin at controlling asthma symptoms.