A Study to Assess the Effect of Particle Size of AZD7594 on Pharmacokinetics (PK) After a Single Inhaled Dose When Administered Using the Dry Powder Inhaler in Healthy Volunteers

The study will comprise: * A Screening period of maximum 28 days. * Three treatment periods during which subjects will be resident prior to the evening meal the 1 day before dosing with AZD7594 (Day -1) until at least 48 hours after dosing; discharged on the morning of Day 3. Subjects will then return for ambulatory visits 72, 96, 144 and 240 hours after dosing, (Day 4, Day 5, Day 7 and Day 11 respectively). * A final Follow-up Visit within 10 days after the last administration of AZD7594. This visit will coincide with the last PK sample collection on Day 11 after the last Treatment Period. There will be a minimum wash-out period of 21 and maximum of 28 days between each dose administration. Subjects will attend a Screening Visit within 28 days before receiving their first dose of AZD7594, if they are found to be eligible, they return for Treatment Period 1, when they will have baseline assessments, and then will be randomized into one of the 6 treatments sequences. For each Treatment Period, the subjects will receive their investigational medicinal product (IMP) dose in the morning of Day 1, will have further assessments for 48 hours after dosing (residential period) and will return to the study center for ambulatory visits 72, 96, 144 and 240 hours after dosing, (Day 4, Day 5, Day 7 and Day 11 respectively). Each subject will receive AZD7594 as a single inhaled dose of 440 µg (nominal dose) of each of the following treatments, administered via Dry powder inhaler (DPI): * Treatment A: Particle size Large * Treatment B: Particle size Medium * Treatment C: Particle size Small Each subject will be involved in the study for up to 12 weeks (up to 4 weeks for enrollment and 8 weeks of active study and Follow-up).