A Study Comparing the Pharmacokinetic, Pharmacodynamic and Safety of CHF 1535 (Fixed Combination of Beclomethasone + Formoterol) Administered Via the NEXT DPI, Versus the Free Combination of Licenced Beclomethasone DPI and Formoterol DPI in Asthmatic Adolescent and Adult Patients.

Main Inclusion Criteria: 1. Male and female adolescents (≥ 12 years old) and adults (≥18 and ≤ 65 years old) 2. Written informed consent; 3. Diagnosis of asthma as defined in the GINA guidelines; 4. Patients with stable asthma, according to the Investigator's opinion; 5. Asthmatic patients already treated with ICS or using short-acting inhaled β2-agonists as reliever to control asthma symptoms; 6. Patients with a forced expiratory volume in one second (FEV1) \> 70% of predicted values; 7. Patients with a peak inspiratory flow (PIF) \> 40 L/min 8. Reversibility test; 9. Non- or ex-smokers; 10. A cooperative attitude and ability to be trained about the proper use of DPI and compliant to study procedures; Main Exclusion Criteria: 1. Pregnant or lactating female; 2. Having received an investigational drug within 2 months before the screening visit 3. Diagnosis of COPD as defined by the current GOLD guidelines; 4. Significant medical history of and/or treatments for cardiac, renal, neurological, hepatic, endocrine diseases, or any laboratory abnormality; 5. Known hypersensitivity to the active treatments; 6. History of drug addiction or excessive use of alcohol; 7. Treatment with a xanthine derivative (e.g. theophylline) formulation in the 4 weeks prior to screening; 8. Hospitalization due to asthma exacerbation or asthma exacerbation within 1 month prior to the screening visit; 9. Inability to perform the required breathing technique and blood sampling; 10. Lower respiratory tract infection within 1 month prior to the screening visit; 11. Blood donation (450 mL or more) or significant blood loss in the 12 weeks before the screening visit.