- A final visit within 5 to 7 days after the last administration of Symbicort. There will be a minimum washout period of 3 days between each dose administration of Symbicort. Subjects will receive single doses of Symbicort on 4 occasions under fasted conditions. During screening, spirometry testing will be performed by a technologist or a qualified designee to ensure subjects perform adequate manoeuvres to achieve optimal lung function. Device and inhalation training will be conducted on admission to each treatment period, and prior to dosing on Day 1 of each treatment period.