Decongestant Activity of Desloratadine in Controlled-Allergen-Exposure Trials

Abstract

Nasal obstruction, which many patients consider to be the most bothersome symptom of seasonal allergic rhinitis (SAR), is generally refractory to oral anti-histamine therapy. Effective resolution of nasal obstruction associated with SAR may help to prevent lower-airway disorders and other adverse sequelae (e.g. otitis media with effusion). Desloratadine, a nonsedating antihistamine with marked inhibitory effects on the early- and late-phase allergic responses, affords significant relief of sneezing, pruritus and rhinorrhoea, as well as nasal congestion. Using the Vienna Challenge Chamber, a closed system that enables rigorously controlled allergen exposure, we observed that a single 5mg dose of desloratadine rapidly and markedly reduced postexposure nasal obstruction in a pilot study. Separately, three randomised, double-blind, placebo-controlled trials demonstrated that desloratadine significantly reduced nasal blockage, as well as acute SAR symptoms, from baseline as compared with placebo over a 5-hour interval in the pollen chamber. The favourable effects of desloratadine on early-phase symptoms were consistent with evidence from controlled-allergen-exposure trials involving other antihistamines (cetirizine, fexofenadine). However, desloratadine also significantly protected against allergen-induced declines in nasal airflow (as assessed by active anterior rhinomanometry) and reduced nasal secretion weights compared with placebo in a controlled-allergen-exposure paradigm. The consistent decongestant effects of desloratadine in pollen-chamber trials were also concordant with data from clinical trials conducted under natural, ambient exposure conditions. Taken together, these findings support the clinical utility of desloratadine, a nonsedating, long-acting, high-affinity H1 receptor antagonist with decongestant properties.