A Study to Investigate How Budesonide and Formoterol Move Through the Body (Pharmacokinetics) When Delivered With Different Devices in Participants Aged 4 to Less Than 12 Years Old With Asthma

This is a phase I single-dose, 2-period cross-over, multicenter study in which the participants will be randomized 1:1 to one of two treatment sequences - AB or BA. In the first study period, participants will receive a single dose of either - 1. Treatment A: Symbicort Aerosphere budesonide/formoterol fumarate × 2 puffs (test formulation) 2. Treatment B: Symbicort pMDI budesonide/formoterol fumarate × 2 puffs (reference formulation) After a washout period of at least 28 days and no longer than 42 days, participants who first received Treatment A will receive a single dose of Treatment B, and participants who first received Treatment B will receive a single dose of Treatment A in the study period 2.