Inclusion Criteria:  Body mass index between 18.5 and 29 kg/m2. Documented clinical diagnosis of stable, persistent, asthma for at least 3 months Subjects who are ICS-naïve for minimum 60 days at Screening Visit. Positive methacholine (MCh) challenge test (concentration of MCh provoking an FEV1 fall of 20% [PC20] < 8 mg/ml or dose of MCh provoking an FEV1 fall of 20% [PD20] < 0.2 mg) in the last year. Post-bronchodilator FEV1 at least 80% of the predicted, documented in the last year. Clinical laboratory test results, 12-lead electrocardiogram (ECG), blood pressure and heart rate (supine) within normal reference range or judged to be not clinically significant by the Investigator. Female subjects of childbearing potential should have a negative pregnancy test at Screening Visit and use a highly effective method of contraception. Reliable subjects who are willing to be available for the duration of the clinical trial and willing to comply with clinical trial procedures. Subjects who have the ability to understand the requirements of the clinical trial. Subjects who have given written informed consent.  Exclusion Criteria:  Current smokers or recent (< 8 weeks) ex-smokers or ex-smokers if > 10 pack-years. Pregnant or breastfeeding female subjects. Inability to carry out pulmonary function testing. FEV1 < 70%. History of near-fatal asthma and/or intensive care unit admission for asthma symptoms. Exacerbations of asthma requiring oral steroids, hospitalization or change in asthma treatment in the previous three months. Evidence of symptomatic chronic or acute respiratory infection in the previous 8 weeks. Diagnosis of chronic obstructive pulmonary disease (COPD) or bronchiectasis. Pulmonary malformations, tuberculosis, cystic fibrosis. History of hypersensitivity or existing contraindication to budesonide or any other Investigational Medicinal Product (IMP) ingredients. Untreated oral candidiasis. Immunosuppressive treatment, including systemic corticosteroids (e.g., oral, parenteral, ocular, nasal), within 28 days before Screening Visit. Use of ICS within 60 days before Screening Visit. Use of anti-leukotrienes, immunoglobulins, beta-blockers, digitalis, amiodarone, antifungals, macrolides, antidepressants, monoamine oxidase inhibitors, antiretroviral drugs, cholinesterase inhibitors, histamine, theophylline, non-steroidal anti-inflammatory drugs, anticholinergic drugs, neuroleptics, curariform drugs, antihistaminic (anti-H1) drugs, calcium channel blockers, long acting beta2-antagonists, mast cell stabilizers (e.g. natrium cromoglycate). History of alcohol or drug abuse. Unstable or life-threatening cardiac disease History or presence of prolonged QT interval (> 470 ms), or any other clinically significant ECG abnormalities as judged by the Investigator based on 12-lead ECG recordings at Screening Visit. Diabetes mellitus. Neuropsychiatric diseases. Clinically relevant laboratory abnormalities at Screening Visit. Blood or plasma donation within 30 days prior to Screening Visit. History or presence of malignancy of any system organ class (other than localized basal cell carcinoma of the skin), treated or untreated, within the past 5 years prior to Screening Visit, regardless of whether there is evidence of local recurrence or metastases. Any surgical or medical condition which might significantly alter the absorption, distribution, metabolism, or excretion of drugs, or which may jeopardize the subject in case of participation in the clinical trial. History or presence of any other clinically relevant disease of any major system organ class (e.g. cardiovascular, pulmonary, renal, hepatic, gastrointestinal, reproductive, endocrinological, neurological, psychiatric or orthopedic disease) as judged by the Investigator. Human immunodeficiency virus (HIV) and severe acute respiratory syndrome (SARS)-CoV-2 infections. Subjects who participated in an investigational trial within the 12 weeks prior to the start of the trial.