Sleep Apnea, Obstructive

Inclusion Criteria

- Participant must be 18 years of age or above at the time of signing the informed consent.
-  Participants need to be diagnosed with OSA but should be considered otherwise healthy at the discretion of the investigator.
-  Participants do not need to be on CPAP therapy at the time of the study. However, if they are on therapy, participants must commit to keep their treatment schedule constant during the study period, especially the night before each administration of study intervention. For participants on CPAP, this will be monitored objectively using the compliance chip within the CPAP devices.
- Female of non-child bearing potential or male.
- Contraceptive use by men or women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.
a. Female participants:
-- i. Participants of non-childbearing potential, i.e. post-menopausal (no menses for at least 1 year) or surgically sterile (documented history of tubal ligation, hysterectomy or bilateral oophorectomy).
b. Male participants:
-- i. Male participants of reproductive potential must agree to utilize two reliable and acceptable methods of contraception simultaneously when sexually active. This applies for the time period between admission to the study site until 12 weeks after the last administration of the study intervention.
Acceptable methods of contraception include, but are not limited to, (i) condoms (male or female) with or without a spermicidal agent; (ii) diaphragm or cervical cap with spermicide; (iii) intra-uterine device; (iv) hormone-based contraception.
- Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.
- Ability to understand and follow study-related instructions.
- The informed consent must be signed before any study specific tests or procedures are done. For Part C reconsent must be signed.

Exclusion Criteria

- Severely impaired breathing within two days prior to randomization (e.g. acute nasal congestion during upper airway infection).
- Subject with known allergies or hypersensitivities to the study drugs (active substances or excipients of the preparations).
- Any other condition which at the discretion of the investigator would make the participant unsuitable for participation in the study and will not allow participation for the full planned study period (e.g. active malignancy or other condition limiting life expectancy to less than 12 months).
- Use of any topical medication containing local anesthetics for nose and throat within 2 days before each administration of study intervention.
- Donation of more than 100 mL of plasma or equivalent volume of blood within 4 weeks or 500 mL whole blood within 3 months before study drug administration.
- Previous participation in this study.
- Participation in another clinical study with study intervention(s) within 90 days prior to first administration.
- Heavy smoking, i.e. more than 20 cigarettes per day.
- Light smokers who are unable to cease smoking for the duration of the inhouse phases of the study (i.e. Study day 1 in treatment periods 1, 2, 3 and 4).
- Drug or alcohol abuse.