In this single center, dose finding, safety study the effect of inhaled Ectoin® inhalation solution will be investigated in subjects with mild bronchial asthma. This dose-finding study will estimate the minimum effective dose and will assess the safe dosage, in terms of the quantity given to patients. The results will be compared to baseline measurements. The results regarding Sputum measurements will be compared to measurements after placebo administration.

Based on the anti-inflammatory effects of inhaled Ectoin® shown in previous animal studies, this trial aims to investigate the effects in terms of a reduction of the unspecific bronchial hyperresponsiveness (BHR) to Methacholine challenge test on subjects with mild bronchial asthma. In addition, measurements of exhaled nitric oxide level as an indicator of bronchial inflammation will be investigated.

This study will focus primarily on safety and dose finding in 12 to 18 subjects with mild bronchial asthma.

After a screening visit, subjects will be treated with placebo, followed by increasing doses of Ectoin® (low, medium and high dose). All doses of Ectoin® inhalation solution and placebo will be administered for 5 - 7 days.

Inclusion Criteria:

• Adults (18 - 65 years)
• FEV1 ≥ 80% of predicted for patient's normal value pre bronchodilator (according to European Coal and Steel Community reference values)
• Positive Methacholine challenge test (PD20 ≤ 0.5 mg)
• A general practitioner or consultant diagnosed mild bronchial asthma
• Non or ex smoker (for more than 6 months, pack years (PY) ≤ 5)

Exclusion Criteria:

• Pregnant or lactating females
• Participation in another clinical study in the previous month
• Severe concomitant disease which may have an impact on the study participation
• Hypersensibility against Ectoin®
• Patients who have had treatment with live attenuated vaccinations within 14 days prior to screening visit (Inactivated influenza vaccination is acceptable, provided it is not administered within 7 days prior to screening visit).
• Other respiratory diseases (e.g. Chronic obstructive pulmonary disease (COPD), cystic fibrosis, alpha-1-Antitrypsin deficiency, sarcoidosis, bronchiectasis, allergic alveolitis, tuberculosis, etc.)
• Upper and lower airway respiratory infection within 4 weeks prior to study start