The study compares Buventol® Easyhaler® and Bufomix® Easyhaler® to the current standard treatment during methacholine challenge test. The trial will also provide inspiratory flow profile data for Easyhaler inhaler.

This trial is designed to provide a further evidence for the use of Easyhaler in diagnostic bronchial challenge tests and on the use of Easyhaler inhaler during obstructive event.

Inclusion Criteria:

1. Written informed consent (IC) obtained.
2. Finnish speaking adult (≥ 18 years old) subject indicated for methacholine challenge test.
3. The subject experiences FEV1 drop ≥ 20% compared to post-diluent spirometry.

Exclusion Criteria:

1. Subjects not eligible for methacholine challenge test for example for any of the following reasons:

   • Any respiratory infection within 2 weeks, or severe respiratory infection within 4 weeks before the study visit
   • FEV1 < 60% of predicted or < 1.0 l
   • Inability to perform acceptable and repeatable spirometry manoeuvres throughout the test procedure
   • Uncontrolled hypertension
   • Acute chest pain or unstable angina pectoris
   • Significant cardiac arrhythmias
   • Pneumothorax or recent bronchoscopy
   • Myocardial infarction or stroke in last 3 months
   • Known aortic aneurysm
   • Recent eye surgery or intracranial pressure elevation risk
   • Cholinesterase inhibitor medication
   • Pregnant or lactating females

2. Subjects who have used the following treatments before the study visit:

   • Short-acting β-agonists within 12 h
   • Long-acting β-agonists within 36 h
   • Ultra-long-acting β-agonists within 48 h
   • Long-acting anti-muscarinic agents within 168 h
   • Short-acting anticholinergics within 12 h
   • Oral theophylline within 24 h
   • Inhaled corticosteroids, leukotriene receptor antagonists and chromones within 4 weeks

3. Known hypersensitivity to the active substance(s) or the excipients of the study treatments (for example severe milk allergy, lactose contains small amounts of milk protein).

4. Administration of another investigational medicinal product within 30 days before the study visit.