The Effect of Intra-sinus Application of Betamethasone Dipropionate Nasal Cream on Patients with Chronic Rhinosinusitis Post Functional Endoscopic Sinus Surgery (FESS)

Inclusion Criteria:

• Adult patients with a clinically confirmed diagnosis of CRS by an otolaryngologist (ENT) undergoing maximal medical therapy as part of their standard of care.

• Having undergone functional endoscopic sinus surgery (FESS) at least 6 months priorto enrolment.

• For each nostril, an endoscopic nasal polyp score of 0, 1, or 2 out of a maximumscore of - (where 0= No polyps, 1= small polyps in the middle meatus not reachingbelow the inferior border of the middle turbinate , 2= nasal polyps reaching belowthe border of the middle turbinate, 3= large nasal polyps reaching the lower borderof the inferior turbinate or nasal polyps medial to the middle turbinate, 4= largenasal polyps causing almost complete obstruction of the inferior nasal cavity) (Gevaert et al, 2023).

• Visible middle turbinates and access to the ethmoid sinuses for dosing asestablished via endoscopic examination.

• Participants must have a > 2 on the disease severity visual analogue scale (VAS) atscreening and pre-treatment.

• Body weight: A minimum body weight >=40 kilograms (kg) and a BMI of ≤ 39 at thescreening visit.

• Individuals of childbearing potential must use adequate birth control methods andnot plan to get pregnant during the study.

• Informed consent: Willingness to give written informed consent and willingness toparticipate in and comply with the study.

• Age ≥18 but <80 years.

Exclusion Criteria:

• Subjects with known hypersensitivity or contraindications to betamethasonedipropionate, mometasone, or topical anaesthesia.

• Subjects with sino-nasal abnormalities, disease, or implanted devices that preventsthe application of the therapy.

• Previous enrolment in this study.

• Subjects currently receiving systemic corticosteroid or have received systemiccorticosteroid in the prior 4 weeks or receiving biologic therapy.

• Subjects with a history of glaucoma or cataracts or have an abnormal intraocularpressure (IOP) at screening or pre-treatment (abnormal IOP is defined as greaterthan 21 mm Hg).

• Subjects with acute sinusitis.

• Subjects with known immunodeficiency.

• Subjects with diabetes (Type 1).

• Subjects with cystic fibrosis.

• Pregnant subjects or subjects trying to get pregnant or currently lactating as theeffect on human pregnancy is unknown.

• Subjects who are unable to give an informed consent because of mental illness,dementia or communication difficulties.

• Subjects with a Cushing's disease diagnosis within the previous 12 months.

• Severe septal deviation and or previous total resection of the middle turbinate.

• Any lab abnormality or underlying medical condition which, in the Investigator'sopinion, should exclude the participant.

• Subjects who are unlikely to comply with study procedures, restrictions andrequirements as determined by the investigator.