Background: Defective nasal barrier function is implicated in allergic rhinitis, which results in persistent inflammation and clinical symptoms, among which congestion plays a prominent role. In searching ways to improve the efficacy of nasally applied drugs in this condition, we tested the hypothesis that hydroxypropylmethylcellulose (HPMC), known as a mucoprotective agent, could enhance the efficacy of a decongestant (oxymetazoline nasal spray, 0.05%) by "sealing" it to the mucosa.
Methods: This double-blind placebo-controlled study was conducted with 40 patients (mean age, 35 years; 23 women) with persistent allergic rhinitis. The patients were randomized to receive 1 puff of oxymetazoline, followed by 1 puff of either HPMC or lactose powder (placebo) twice a day for 7 days and then only oxymetazoline rescue medication for another week. Peak inspiratory nasal flow (PNIF) was measured for 360 minutes after oxymetazoline and HPMC or placebo insufflation on days 1 and 8, and at a single point on day 15. Symptoms assessments involve visual analog scales and total nasal symptom scores.
Results: HPMC significantly enhanced oxymetazoline-increased PNIF at days 1 (p = 0.042) and 8 (p = 0.006). Baseline PNIF was greater in the HPMC group at day 15 (p = 0.014), indicative of further reduced nasal congestion. All nasal symptoms improved in both groups at day 8, but only the HPMC group showed further amelioration at day 15. Rescue medication was smaller in the HPMC group between days 8 and 15.
Conclusion: HPMC enhances decongestion through mucoadhesion but may also be augmenting the mucosal barrier in allergic rhinitis, which explains the carryover efficacy of oxymetazoline for a week after its discontinuation.
Clinical trial registration: clinicaltrials.gov identifier: NCT01986582.