Inclusion Criteria:

• Patients must have given their informed consent before commencing the procedures specified in the protocol, indicating that they understand the objectives of the study and are willing to adhere to the procedures described in the protocol.
• Males or females.
• Patient aged between 16 and 65 years.
• Out patients.
• Non smokers or ex-smokers, having stopped smoking > 1 year.
• Moderate persistent or severe asthma, according GINA classification
• Patients with an established (i.e. at least one year) clinical history of asthma.
• Absence of long-term remissions of asthma (lasting more than 1 month)
• Poorly controlled asthma, due to various reasons.
• Patients with a FEV1 reversibility of at least 12% from initial level after 400 mcg salbutamol inhalation (4 puffs of salbutamol MDI, 100 mcg per puff). Patients whose FEV1 reversibility was 12% within the past 12 months are acceptable, providing that the records are available to the investigator.
• Patients able to swallow capsules, able to understand and complete diary cards and to record their PEFR using a peak-flow meter.

Exclusion Criteria:

• Long-term history of smoking (3 years and more)
• History or presence of cardiovascular, renal, neurologic, psychiatric, liver, immunologic, endocrine, infection or other diseases or dysfunctions if they are clinically significant. A clinically significant disease is defined as one which in the opinion of the investigator may either put the patient at risk because of participation in the study or a disease which may influence the results of the study or the patient's ability to participate in the study.
• Patients with a recent history (< 1 year) of myocardial infarction and/or (< 3 years) of heart failure or patients with any cardiac arrhythmia requiring drug therapy.
• History of cancer within the past 5 years.
• Patients with active tuberculosis with indication for treatment.
• Patients with a history of cystic fibrosis, bronchiectasis, chronic bronchitis or emphysema.
• Patients with clinically significant abnormal baseline haematology, blood chemistry or urinalysis or if the abnormal defines a disease listed as an exclusion criterion.
• Patients with known allergy, side effects, intolerance/hypersensitivity to investigational drug
• Patients currently using MAO inhibitors, tricyclic antidepressants, antiepileptic drugs, narcotic agents.
• Pregnant or nursing women and sexually active women with childbearing potential not using a medically approved method of contraception.
• Patients unlikely, unable or unwilling to comply with the requirements of the protocol.