Nasal Carbon Dioxide Used As Needed in the Symptomatic Treatment of Seasonal Allergic Rhinitis.

Abstract

Nasal, noninhaled carbon dioxide (CO₂) was shown to be effective for the treatment of symptoms of seasonal allergic rhinitis (SAR) and perennial allergic rhinitis in single application studies. To assess the efficacy of as-needed treatment with nasal, noninhaled CO₂ in patients with SAR. Fifty-six ragweed-allergic patients were enrolled at 3 sites in this study. After a 3- to 7-day run-in, 32 eligible patients who had an instantaneous total nasal symptom score of 8 or more out of a maximum of 12 in at least 2 SAR episodes per day were randomized to the CO₂ group (n = 19) or to the placebo group (n = 13). A 10-second/nostril application was used as needed for 14 days (maximum 6 times/d). Patients evaluated their symptoms before and 30 minutes after each application. All symptoms were scored on a 0 to 3 scale. Analysis of all treated episodes (CO₂ = 816, placebo = 516) showed a statistically significant beneficial change in total nasal symptom score from baseline (effect size = -0.51; P < .001). The effect size was larger with more severe baseline symptoms (baseline severities of ≥6 = -0.98; ≥8 = -1.14; and ≥10 = -1.61; all P < .001). CO₂ was well tolerated, with transient nasal discomfort as the most common adverse event reported. There were no serious adverse events, serious adverse device effects, or early discontinuations. Nasal, noninhaled CO₂ is effective for the as-needed treatment of SAR symptoms. The effect is rapid and the effect size is large. It represents a novel potential option for the as-needed treatment of rhinitis symptoms.