Baseline Visit (day -1) The day before the first drug administration, patients will attend the clinical research unit and diary cards will be reviewed. In order to enter the study the patients must have a mean total daily symptom score >/= 4 measured during the last 7 days of the baseline run-in period [A symptom scale with scores ranging from 0 (=symptom free) to 3 (=severe symptoms) is used, with 6 questions, and a total maximum daily symptom score of 18, see appendix D)] and/or have a >/= 10% and < 30% diurnal variation in PEFR measured on at least 2 of 7 days during the same period.