Dose-Response of Salmeterol in Children

During the study the subject will have to attend 4 study visits: 2 screening visits and 2 treatment visits. Before each study visit, the subject has to stop using certain asthma medications. At Screening Visit 1a, the parent/guardian will read and sign the informed consent form to allow the subject to take part in this study. The subject, if appropriate, will be asked to sign the last page to indicate his/her assent to be in the study. The study coordinator will conduct an interview to find out about the subject's medical history, diseases other than asthma, previous medication and any medication that the subject will take during his/her participation in this study. Vital signs, i.e. blood pressure, heart rate, and respiration, and height and weight will be measured, and an electrocardiogram (ECG) which is a test to measure the electrical activity of the subject's heart, will be performed. The subject will be examined by a Pediatric Pulmonary physician and will be taught the proper way to use a Diskus® inhaler. The subject has to be able to show that he/she can do this correctly. At Screening Visit 1b, if all of the tests are in the appropriate range the subject will take 2 puffs of Flovent from a Diskus®. One hour later, the subject will perform a breathing test called impulse oscillometry. Essentially, a sound is sent down into the lungs and a computer converts the return sound into a number. Then the subject will begin a breathing test with methacholine, a drug that makes the airways smaller. He/she will begin by inhaling a low dose in a nebulizer and then performing oscillometry. After a 5 minute interval he/she will breathe in increasing doses, up to 6 times or until his/her breathing test increases by 40%. Albuterol will be administered immediately after the end of the challenge and the subject will be monitored until his/her breathing returns to within 20% of where it was before the challenge. If the methacholine test results are within the appropriate range the subject will be eligible for the treatment phase and will be scheduled for Visit No. 2. At each treatment visit, the subject will take 2 puffs of study drug from two Diskus® inhalers, either 1 puff of Flovent and 1 puff of Advair, or 1 puff of Advair from two different inhalers. This is done in a blinded manner so the study coordinator does not know which treatment is used each time. There will be a 1 hour wait time after the medication is administered before the methacholine challenge is started. Albuterol will be administered immediately after the end of the challenge and the subject will be monitored until his/her breathing returns to within 20% of where it was before the challenge.