This is a single blind, single dose, crossover study to investigate the relative efficacy of terbutaline Turbuhaler® 0.4 mg in relation to salbutamol pressurized Metered Dose Inhaler (pMDI) 200 μg in Japanese adult asthmatic patients.The secondary objective of this study is to investigate safety of terbutaline Turbuhaler® 0.4 mg in Japanese adult asthma patients by means of adverse events (AEs) and vital signs (blood pressure, pulse rate). The subject population includes Japanese patients (16 years of age or older) with asthma who need treatment with inhaled Glucocorticosteroids (ICS).

Inclusion Criteria:

• On ICS for at least 3 months from Visit 2 and with a prescribed constant dose during the 4 weeks prior to Visit 2
• Forced Expiratory Volume in 1 Second (FEV1) of at least 50 % of predicted normal value pre-bronchodilator
• Reversible airway obstruction according to reversibility test performed at Visit 2, defined as an increase in Forced Expiratory Volume in 1 Second (FEV1) ≥12% relative baseline at 15-30 minutes after inhalation of in total 400 μg salbutamol

Exclusion Criteria:

• Treatment with oral, parenteral or rectal GCS (Glucocorticosteroids)within 4 weeks or depot parenteral GCS (Glucocorticosteroids) within 3 months prior to Visit 2.
• Change in prescribed asthma medication due to exacerbation of asthma within 4 weeks prior to Visit 2 or being hospitalized due to exacerbation of asthma within 8 weeks prior to Visit 2.