Buparid/PARI SINUS Versus Budes® Nasal Spray in the Therapy of Chronic Rhinosinusitis With Polyposis Nasi

Inclusion Criteria: * Patient with confirmed diagnosis of chronic rhinosinusitis (CRS) with polyposis nasi grade I-III * Patient with a PNIF of \> 7 l/min separated for left and right side of the nose * Patient's written informed consent * Male or female,\>= 18 years of age * Patient is able to undergo nasal therapy without restrictions * Capable of understanding the purpose and risk of the clinical trial * Female patients with childbearing potential must have a negative urine pregnancy test prior to first IMP administration * Patient has completed correctly the diary during the Wash-in Phase Exclusion Criteria: * Patients with cystic fibrosis * Patients with polyposis nasi grade IV * Patients with prior sinonasal surgery (exemption: polypectomy) * Patients with primary ciliaritis * Pregnant or breastfeeding women * Patients with suspected active upper airway infection * Receipt of an investigational drug as part of a clinical trial within 4 weeks prior to first administration of IMP * Drug or alcohol abuse * End-stage malignancies * Known hypersensitivity to Budesonide * Patients with oral steroid therapy within the last 4 weeks * Patients with frequent epistaxis (\> 2 per month)