This Phase IV study is an a multi-centre, randomised open label, two way cross-over design to evaluate the efficacy, safety, and tolerability of NEUMOTEROL 400 in subjects with asthma. The study will be used to demonstrate the non-inferiority of Budesonide/Formoterol Fumarate combination (BFF) 400/12 micrograms (mcg) single capsule inhaler (NEUMOTEROL 400) compared with BFF 320/9 mcg SYMBICORT Forte TURBUHALER® inhaler.