Patient description: A 39-year-old man came to the clinic with cough and shortness of breath that was not relieved by his inhaler. He had these symptoms for 5 days during the past 2 weeks. He doubled his oral corticosteroids in the past week. He is a chef with a history of asthma for 3 years, suffering from frequent cough, wheezing, and shortness of breath and chest tightness. The symptoms become more bothersome within 1-2 hours of starting work every day and worsen throughout the work week. His symptoms improve within 1-2 hours outside the workplace. Spirometry was performed revealing a forced expiratory volume in the first second (FEV1) of 63% of the predicted. His past medical history is significant for seasonal allergic rhinitis in the summer. He doesn't smoke or use illicit drugs. His family history is significant for asthma in his father and sister. He currently uses inhaled corticosteroid (ICS) and fluticasone 500 mcg/salmeterol 50 mcg, one puff twice daily.

Clinical trial eligibility criteria: eligible ages (years): 18.0-75.0,  Asthma Provision of informed consent before any study specific procedures. 2. Men or non-pregnant, non-lactating women 18 to 75 years of age, inclusive. 3. Non-smoker or ex-smoker (quit ≥6months prior to Visit 1) with a total smoking history of ≤10 pack years. 4. Documented clinical diagnosis of asthma for ≥6 months before Visit 1 according to GINA guidelines. 5. On stable dose of ICS or ICS/LABA FDC, for at least 1 month prior to Visit 1, at the doses approved in the country of enrolment. 6. Prebronchodilator FEV1 at Visit 2 ≥40% and ≤85% of predicted (1 repetition of the test is allowed before screen failure). 7. Reversibility to salbutamol (per American Thoracic Society (ATS)/European Respiratory Society (ERS) 2005 ie, ≥12% and ≥200 mL) at Visit 2 (1 repetition of the test is allowed before screen failure). 8. Demonstrate the ability to use the study inhalation device properly. 9. Able to perform repeated pulmonary function testing for FEV1. 10. Able to read, speak and understand German. 11. Patient must agree to all restrictions during the study  Involvement in the planning and/or conduct of the study (applies to both AstraZeneca staff and/or staff at the study site). 2. Participation in another clinical study with an IP during the last 3 months. 3. Known or suspected hypersensitivity to the IP or excipients, including lactose (Note: lactose intolerance is not an exclusion). 4. Systemic steroid use in the 6 weeks before Visit 1. 5. Hospitalization due to asthma in the 6 months prior to Visit 1. 6. Any active pulmonary disease other than asthma. 7. Non-compliance with study procedures in the run in period as judged by the Investigator. 8. Treatment with biologicals such as monoclonal antibodies or chimeric biomolecules including omalizumab within 6 months or 5 half-lives before Visit 1 (whichever is longer). 9. Treatment with any investigational drug within 30 days or 5 half-lives (whichever is longer) prior to Visit 1. 10. Plasma donation within 1 month of screening or any blood donation/loss more than 500 mL during the 3 months prior to Visit 1. 11. Any laboratory abnormality or suspicion of any clinically relevant disease or disorder (on history or examination), including uncontrolled hypertension or uncontrolled diabetes, which, in the opinion of the Investigator, may either put the patient at risk because of participation in the study, or influence the results or the patient's ability to participate in the study, or any other safety concerns in the opinion of the Investigator. 12. Known chronic hepatitis or HIV infections at the time of enrolment. 13. Any active malignancy or treatment thereof within the 3 years prior to enrolment. 14. Any clinically important abnormalities in rhythm, conduction, or morphology of the screening 12-lead ECG as judged by the Investigator on the screening ECG. 15. Prolonged QT interval using Fridericia's correction 450 msec for males and 470 msec for females on the screening ECG or family history of long QT syndrome. 16. PR (PQ) interval prolongation (> 240 msec), intermittent second or third degree atrialventricular (AV) block or AV dissociation on the screening ECG. 17. Implantable cardiac defibrillator and patients with sustained symptomatic ventricular and/or atrial tachyarrhythmia. 18. Any contraindication against the use of sympathomimetic drugs as judged by the Investigator. 19. Unstable angina pectoris or stable angina pectoris classified higher than Canadian Cardiovascular Society Class II, or a myocardial infarction, or stroke within 6 months before Visit 1. 20. History of hospitalisation within 12 months caused by heart failure or a diagnosis of heart failure higher than New York Heart Association Class II. 21. Suspected poor capability to follow instructions of the study, as judged by the Investigator. 22. History of or current alcohol or drug abuse (including marijuana), as judged by the Investigator. 23. Planned in-patient surgery, major dental procedure or hospitalisation during the study. 24. Involvement in the planning and/or conduct of the study (applies to AstraZeneca staff, contract research organisation staff and/or staff at the study site). 25. Vulnerable persons (eg, persons kept in detention). 26 Daily rescue medication (salbutamol) use of ≥ 12 puffs for ≥ 3 consecutive days during the run-in period. 27. Patient who intends to use any concomitant medication not permitted by this protocol or not to meet the restrictions. 28. Patient on treatment with strong CYP3A4 inhibitors such as ketoconazole or itraconazole or CYP3A4 inducers such as rifampin at Visit 1. 29. Procedures for withdrawal of incorrectly enrolled patients