Lung scans could show which asthma inhaler hits the right spot

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Male or female patient ≥ 18 years old. 2. Written informed consent obtained. 3. Patient with a documented diagnosis of asthma according to the Global Initiative for Asthma (GINA) guidelines 4. Patient with a co-operative attitude and ability to correctly use the DPI. 5. Female patient of childbearing potential who confirm that a reliable method of contraception was used at least 14 days before visit 1 and will continue to use a reliable method of contraception during the study, or post-menopausal women (at least 12 months of amenorrhea) 6. Patient must be stable and treated in accordance with the GINA guidelines. 7. Patient must be a non-smoker or ex-smoker who have stopped smoking at least 1 month prior to visit 1 and has a smoking history of \< 10 pack years. 8. Patient must be able to understand and complete the protocol requirements, instructions, questionnaires and protocol-stated restrictions. Exclusion Criteria: 1. Pregnant or lactating female. 2. Unstable patient who developed an asthma exacerbation in the 4 weeks before screening. 3. Patient with upper or lower airways infection in the 4 weeks before screening. 4. Patient unable to perform pulmonary function testing. 5. Patients unable to withdraw fixed combination or long acting bronchodilator inhalation products 6. Patient with an uncontrolled disease or any condition that might, in the judgement of the investigator, place the patient at undue risk or potentially compromise the results or interpretation of the study. 7. Patient with active lung cancer or any other chronic disease with poor prognosis and /or affecting patient status. 8. Patient with allergy, sensitivity or intolerance to study drugs and/ or study drug formulation ingredients. 9. Patient unlikely to comply with the protocol or unable to understand the nature, scope and possible consequences of the study. 10. Patient who received systemic corticosteroids within the last 4 weeks prior to visit 11. Patient who received any investigational new drug within the last 4 weeks prior to visit 1 and is participating in any clinical trial. 12. Patient with a history of alcohol or substance abuse that in the opinion of the investigator may be of clinical significance 13. Patient with diagnosis of Chronic Obstructive Pulmonary Disease (COPD). 14. Patients who has a lactose intolerance or history of allergy to milk proteins. 15. Patients treated with medications or herbal medicines that are strong cytochrome P450 3A4 (CYP3A4) inhibitors (e.g., ritonavir, indinavir, nelfinavir, saquinavir, atazanavir, ketoconazole, itraconazole, voriconazole, fluconazole, cyclosporine, mibefradil, nefazodone, clarithromycin, telithromycin, troleandromycin, norfloxacin, ciprofloxacin) or inducers (e.g. phenobarbital, phenytoin, barbiturates, carbamazepine, oxcarbazepine, rifabutin, rifampin, St John's wort) within 2 weeks prior to Screening Visit and during the study.