The purpose of this study is to confirm equivalent bronchodilator efficacy of the test product compared to the reference product.

Main inclusion criteria:

• Written informed consent
• Asthma diagnosis for at least 6 months
• Prebronchodilator FEV1 45-90% of the predicted value
• Demonstration of reversible airway obstruction
• Stable asthma on the same regular treatment for at least 4 weeks before the study
• Non-smoker for at least 6 months before the study

Main exclusion criteria

• Respiratory infection within 4 weeks before the study
• Smoking history of more than 10 pack-years
• Other severe chronic respiratory disease than asthma
• Concurrent illness that would interfere with the interpretation of the study results or constitute a health risk for the patient if he/she takes part in the study
• Corrected QT interval > 450 ms in males or > 470 ms in females
• Abnormal serum potassium value or other clinically significant laboratory finding
• Systolic blood pressure over 180 mmHg and/or diastolic blood pressure over 100 mmHg
• Treatment with a long-acting β2-agonist, a xanthine-derivative, a β-blocker or with a corticosteroid (other than inhaled) within 4 weeks before the study
• Use of drugs that prolong QT-interval
• Women who are pregnant, breast-feeding or without reliable contraception
• Participation in another clinical drug study