Volume 10 Supplement 1

Canadian Society of Allergy and Clinical Immunology Annual Scientific Meeting 2013

Open Access

Double blind randomized crossover trial of PF-03654764+fexofenadine in the environmental exposure unit (EEU)

  • Michelle L North1, 2,
  • Terry Walker2,
  • Lisa M Steacy2,
  • Barnaby G Hobsbawn2,
  • Richard J Allan3,
  • Frances Hackman3,
  • Xiaoqun Sun4,
  • Andrew G Day4 and
  • Anne K Ellis1, 2, 5
Allergy, Asthma & Clinical Immunology201410(Suppl 1):A68


Published: 3 March 2014


Oral histamine receptor–1 antagonists, such as fexofenadine, offer suboptimal relief of allergic rhinitis-associated nasal congestion. Combinations with oral sympathomimetics, such as pseudoephedrine, relieve congestion but produce side effects. Histamine receptor-3 antagonists, such as PF-03654764, reduce congestion in animals and have been proposed as novel therapeutics. Previous nasal allergen challenge studies of similar H1+H3 receptor antagonist combinations demonstrated reduced congestion. Herein we employ the Environmental Exposure Unit (EEU) to conduct the first randomized controlled trial of PF-03654764 in allergic rhinitis. The primary objective was to compare the effect of PF-03654764+fexofenadine to pseudoephedrine+fexofenadine on the subjective measures of congestion and Total Nasal Symptom Score (TNSS). The objective of post-hoc analyses were to compare all treatments to placebo and determine the onset of action (OA).


64 participants were randomized in a double-blind, placebo-controlled 4-period crossover study. Participants were exposed to ragweed pollen for 6 hours post-dose in the EEU.


PF-03654764+fexofenadine was not superior to pseudoephedrine+fexofenadine. In post-hoc analyses, PF-03654764+fexofenadine significantly reduced TNSS, relative to placebo, and OA was 60 minutes. Pseudoephedrine+fexofenadine significantly reduced congestion and TNSS, relative to placebo, with OA of 60 and 30 minutes, respectively. All PF-03654764-treated groups experienced an elevated incidence of adverse events.


PF-03654764+fexofenadine failed to provide superior relief of allergic rhinitis-associated nasal symptoms upon exposure to ragweed pollen compared to fexofenadine+pseudoephedrine. However, PF-03654764+fexofenadine improved TNSS compared to placebo. Side effects were not insignificant.

Authors’ Affiliations

Department of Biomedical and Molecular Sciences, Queen’s University
Allergy Research Unit, Kingston General Hospital
Pfizer Ltd.
Clinical Research Centre, Kingston General Hospital
Division of Allergy and Immunology, Department of Medicine, Queen’s University


© North et al; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.