TRPV1 inhibition does not prevent cold dry air-elicited symptoms in non-allergic rhinitis.

ABSTRACT

BACKGROUND: The transient receptor potential vanilloid 1 (TRPV1)-expressing sensory C-fibers may play a role in the development of nasal hyper-responsiveness and symptoms of non-allergic rhinitis (NAR). OBJECTIVE: To evaluate the effects of a TRPV1-antagonist, SB-705498, on cold dry air (CDA)-induced symptoms in patients with NAR. METHODS: This randomized, double-blind, placebo-controlled, crossover study evaluated 14 days of once daily, topical intranasal SB-705498 12 mg in 40 patients with NAR using a CDA challenge experimental model in an environmental exposure chamber (EEC, Cetero Research, Mississauga, Ontario). The primary endpoint was total symptom score (TSS), expressed as weighted mean over 60 minutes (WM0-60) or maximum TSS at 1 hour and 24 hours postdosing. RESULTS: Treatment with SB-705498, relative to placebo, did not improve WM0-60 or maximum TSS at 1 hour and 24 hours post-dosing on days 1 or 14. Mean (95% CI) treatment differences (SB-705498 - placebo) on day 14 were, for WM0-60 at 1 hour -0.12 (-0.60, 0.36); for maximum TSS at 1 hour -0.03 (-0.58, 0.51). SB-705498 had no impact on any other efficacy parameters. SB-705498 was well tolerated and pharmacokinetics analysis supported the dosing regimen. CONCLUSION: SB-705498 12 mg for 14 days did not alleviate the CDA-induced symptoms of NAR. Despite engagement of the TRPV1 receptor, there was no translation to clinical efficacy, suggesting redundancy in symptom pathways.