A Study to Investigate the Safety, Tolerability, and Pharmacokinetics (PK) of Oral AZD6793 in Healthy and Chronic Obstructive Pulmonary Disease Participants, to Assess the Relative Oral Bioavailability Between Two Formulations, and the Food Effect on the PK of AZD6793 Compared to Fasting State.

Parts 1, 2, and 3 were conducted in a single center and Part 4 is conducted in 2 centers. Part 1 of the study will comprise: * A Screening Period of maximum 28 days (Day -29 to Day -2) * A Treatment Period during which participants will be resident at the Clinical Unit from Day -1 (the day before IMP administration \[Day 1\]) until at least 72 hours after IMP administration. Participants will then be discharged on Day 4 if in good health and after all samples have been collected. Depending on the emerging data, the length of the stay at the Clinical Unit may be changed. * A Follow-up Visit within 6 ± 1 days after the IMP dose (this visit may be done later if indicated, for example, if emerging PK data indicates a longer AZD6793 half-life than was predicted). Part 2 of the study will comprise: * A Screening Period of maximum 28 days (Day -29 to Day -2). * A Treatment Period during which participants will be resident at the Clinical Unit from Day -1 (the day before first IMP administration \[Day 1\]) until Day 10. participants will receive a single dose of IMP in the morning on Day 1. After a washout of at least 48 hours (depending on PK data from Part 1), participants will be dosed twice daily (12 hours apart) from Day 3 through Day 7. Participants will receive the last dose of IMP in the morning of Day 8. Participants will then be discharged on Day 10 if in good health and after all samples have been collected. * A Follow-up Visit within 6 ± 1 days after the last IMP dose (this visit may be done later if indicated, for example, if emerging PK data indicates a longer AZD6793 half-life than was predicted). Part 3 of the study will comprise: * A Screening Period of maximum 28 days (Day -29 to Day -2). * A Treatment Period during which participants will be resident at the Clinical Unit from Day -1 until Day 3. Participants will be randomised on Day 1 of Visit 3 to one of 3 treatment sequences and will receive AZD6793 on Day 1 of each treatment period. Dose administration will be separated by a washout period of at least 3 days from the previous IMP dose of each treatment period. * A Follow-up Visit within 6 ± 1 days after the last IMP dose Part 4 of the study will comprise: * A Screening Period of maximum 35 days (Day -35 to -2) * A Treatment Period of up to 28 days (at least 26 days) of dosing with AZD6793 or placebo. The participants will be admitted to the Clinical Unit on Day -1 and will receive single dose of AZD6793 or placebo on Day 1 and discharged from the Clinical Unit in the evening on Day 1 (12 hours post-dose). * A Follow--up Visit 6 ± 2 days after the last IMP dose