In vitro and in vivo Evaluation of the Efficacy and Safety of Powder Hydroxypropylmethylcellulose as Nasal Mucosal Barrier

INTRODUCTION: Insufflation of powder hydroxypropylmethylcellulose (pHPMC) in the nose has been proven an effective barrier in subjects with rhinitis in many clinical studies. We conducted additionally in vitro and in vivo experiments to address outstanding efficacy and safety issues. METHODS: We used an experimental setup to demonstrate the inhibition of the diffusion of allergen extracts (house dust mite, Japanese cedar, Ragweed, Timothy grass) and pollutants (particulate matter 2.5 µm, PM2.5). Safety of pHPMC when insufflated in the airways of rats was assessed in 24 animals which were sacrificed; tissue sections from lungs, brain and liver were made 1, 24 and 48 hrs after pHPMC inhalation and compared to those of control animals. RESULTS: pHPMC acted as an effective barrier to diffusion of both the liquid allergen extracts and of PM2.5 into the agar covered slides: the quantities of the other tested allergens ranged between <0.5% and 14% of the quantities diffused in the void slides after 6 hrs. The quantity of PM2.5 penetrating the agar was reduced by 94%. Histological photomicrographs did not reveal any evidence of inflammation at 1, 24 and 48 hrs after pHPMC insufflation. CONCLUSION: Use of pHPMC should be viewed as a barrier enforcing measure against inhalatory ambient intruders.