BI 671800 in Asthmatic Patients on Inhaled Corticosteroids

Inclusion criteria: 1. Signed informed consent consistent with ICH-GCP 2. Three month history of reversible (12% and 200 mL in forced expiratory volume in one second - FEV1) asthma (according to GINA) with following spirometry at randomisation: FEV1 60%- 85%. 3. Stable inhaled corticosteroids (iCS) dose 3 months prior to screening. 4. Diagnosis of asthma prior to 40 years. 5. Asthma Control Questionnaire (ACQ) at least 1.5 at randomisation. 6. Male or female 18 to 65 years. 7. Non-smokers or ex-smokers (less than 10 pack years history) with negative cotinine screen. 8. Able to perform pulmonary function testing. Exclusion criteria: 1. Significant diseases other than asthma or allergic rhinitis. 2. Hepatic transaminases or total bilirubin greater than 1.5 ULN. 3. Hospitalisation for asthma exacerbation or asthma related intubation within 3 months. 4. Uncontrolled asthma on iCS + other controller. 5. Respiratory tract infection or exacerbation within 4 weeks. 6. FEV1 less than 40%, more than 12 puffs rescue salbutamol on more than two consecutive days, or asthma exacerbation during run-in period. 7. Participation in another interventional study. 8. Pregnant or nursing women. 9. Women of child bearing potential not using appropriate methods of birth control as defined by the study protocol.