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).