 During this study, your child will need to attend up to 5 office visits and maintain regular telephone contact with the clinic. Certain office visits will include physical exams, medical history review, exercise challenge test walkingrunning on a treadmill, electrocardiogram ECG tests, and lung function tests. All study related medications and medical examinations are provided at no cost. All study drugs are currently available by prescription to patients 4 years and older. 