Levocetirizine better protects than desloratadine in a nasal provocation with allergen

Abstract

BackgroundDirect comparisons of antihistamines are rare but very much needed. Newly available antihistamine preparations, levocetirizine, the R-enantiomer of racemate cetirizine, and desloratadine, an active metabolite of loratadine, have been recently released for allergic rhinitis. ObjectiveWe sought to compare levocetirizine and desloratadine in a nasal provocation test (NPT) with grass pollen. MethodsTwenty-four volunteers with grass pollen allergy and a history of rhinitis were enrolled in a double-blind, placebo-controlled, crossover study. Three NPTs were performed in a dose-escalating manner during the out-of-season period 4 hours after a single dose of levocetirizine (5 mg), desloratadine (5 mg), or placebo. ResultsDifferences in the mean allergen dose level (primary end point) necessary to reach the NPT threshold indicated improved protection provided by levocetirizine compared with that provided by desloratadine (P=.02). Sneezing and rhinorrhea were better inhibited by levocetirizine than desloratadine. Nasal congestion, as assessed by using objective methods, was not limited by either active substances or placebo. In nasal lavage fluid, IL-5, IL-8, eotaxin, and eosinophil cationic protein levels increased at 24 hours, without differences between the groups. In contrast, levocetirizine, but not desloratadine, significantly limited albumin extravasation into nasal lavage fluid in the early-phase response. ConclusionsThis study demonstrates a better overall protection of a single dose of levocetirizine compared with desloratadine in an NPT with grass pollen allergen. In contrast to late-phase inflammatory markers, which were unaffected, extravascular leakage of the early-phase marker albumin was significantly limited by levocetirizine.