Comparing the Efficacy of Bricanyl M2 and Bricanyl M3 at 0.5 and 1.5 mg Dose Levels, to Allow for a Switch From Bricanyl Turbuhaler M2 to Bricanyl Turbuhaler M3

Inclusion Criteria: - Female and male aged 18 and 65 years. * At least 6 months of documented clinical diagnosis of asthma as defined by GINA 2012 or American Thoracic Society (Expert Panel Report 3 2007) prior to visit 1 * Stable asthmatics on SABA alone, on low dose ICS (200-400 µg budesonide corresponding) or on fixed combination of low ICS/LABA * At the enrolment visit 1a, the visit baseline FEV1 must be ≥80 % of that predicted normal (NHANES III). For LABA patients the visit baseline FEV1 must be ≥80 % of that predicted normal (NHANES III) at both visit 1a and visit 1b. If not, the patient will be withdrawn from the study * At the enrolment visits 1a or 1b (LABA patients only) and at the end of run-in period, visit 2, eligible patients should demonstrate an airway responsiveness to methacholine PC20 \<8 mg/mL. If not, the patient will be withdrawn from the study * Capable of using Turbuhaler inhalation device as judged by investigator. Exclusion Criteria: Diagnosed with COPD or history of cystic fibrosis, bronchiectasis or other respiratory diseases * Pregnancy, breast-feeding, lactation, or planned pregnancy during the study. Fertile women not using acceptable contraceptive measures * Conditions which could alter airway reactivity to methacholine (e.g. pneumonia, upper respiratory tract infection, viral bronchitis and/or sinobronchitis) within past six weeks * Exacerbation due to asthma or change in asthma medication during the last 3 months prior to enrolment * Night time awakenings due to asthma symptoms on 2 consecutive nights during the last 4 weeks prior to enrolment * Smokers 6 months prior to the study start or with a history of smoking of more than 10 pack years (e.g. 20 cigarettes/day for at least 10 years, or 10 cigarettes/day for at least 20 years, or equal).