Intranasal capsaicin is lacking therapeutic effect in perennial allergic rhinitis to house dust mite. A placebo-controlled study

Background In a recent placebo-controlled study we demonstrated that capsai cin is an efficacious substance in the treatment of non-allergic non-infect ious rhinitis. In this study the therapeutic effect lasted more than 9 mont hs. This effect was not based on modulation of inflammation. Objective To evaluate the effect of repeated application of capsaicin to pa tients with a nasal allergy to house dust mites (HDM), using the same treat ment protocol as recently introduced in the treatment of non-allergic patie nts. Methods Twenty-six patients with rhinitis, 15 females and 11 males (range: 20-46 years; mean 30.5), allergic to HDM were treated with either capsaicin or placebo in a double-blind, placebo-controlled, parallel group design. N asal reactivity to HDM expressed as nasal symptoms, albumin and leukotriene levels in nasal lavage fluid and responsiveness to histamine, assessed as symptoms before and 6 weeks after treatment, were used to compare both trea tment groups. In addition, visual analogue scales and rhinitis quality of l ife (RQL) assessment before, 6 weeks after and 3 months after treatment wer e used as outcome variables. Results No significant effect of capsaicin on nasal challenge tests with HD M (nasal symptoms, albumin and leukotriene levels), on VAS or RQL outcome 6 weeks or 3 month's after treatment, was demonstrated. Capsaicin did have a small effect on the area of the curve (AUC) of histamine dose response cur ves (P = 0.03). Conclusion Desensitization with capsaicin in doses sufficient to control sy mptoms in patients with severe non-allergic rhinitis is lacking therapeutic effect in perennial allergic rhinitis.