Nasal Application of Powder vs. Liquid Cellulose Derivatives to Suppress Allergen Challenge

RATIONALE: Covering the nasal mucosa with a layer of inert material can be considered as an alternative to allergen avoidance and is referred to as a ‘barrier-enforcing measure’. Numerous semi-synthetic cellulose derivatives are promising candidates for this approach because of their ability to retain water, thicken, and to form films when applied to the mucosal surface. We compare the efficacy of two different cellulose-derived formulations, a powder and a liquid one, to supress the response to nasal allergen challenge.

METHODS: Two separate double blind placebo-controlled cross over clinical trials were conducted in subjects with allergic rhinitis. The first study was carried out in 15 adult subjects sensitized to house dust mites, in whom cellulose derived powder was insufflated (Cellulose-P) prior to the challenge. The second study was performed out of season in 20 adult subjects sensitized to grass pollen and ragweed, in whom a different brand of cellulose was instilled as a liquid (Cellulose-L). The documented common outcomes were total nasal symptom scores (TNSS) and peak nasal inspiratory flow (PNIF).

RESULTS: In the Cellulose-P study the differences between the active and placebo challenges indicated significant suppression of the PNIF decrease (P=0.05), while no statistical difference emerged for this outcome in the Cellulose-L study (P=0.31). The findings for TNSS followed patterns similar to the results of PNIF.

CONCLUSIONS:

The powder cellulose derivative had significant effects in suppressing the consequences of a nasal allergen challenge, while the liquid cellulose derivative did not prove to be significantly better than placebo.