As a summary of the clinical implications states, “Second-generation H1 receptor antagonists improve most symptoms of allergic rhinitis except nasal congestion. An oral H3 receptor antagonist decreased nasal congestion with an oral H1 receptor antagonist.”
The study, sponsored by Pfizer, used a randomized, double-blind, double-dummy, placebo-controlled, 4-way crossover design to investigate the effect of adding an investigational H3 antagonist designated PF-03654746 to fexofenadine in 20 patients with out-of-season allergic rhinitis.
Dr. Thomas B. Casale, at Creighton University in Omaha, Nebraska, and colleagues assigned the participants in random order to treatment with 10 mg of PF-03654746 + 60 mg of fexofenadine, 1 mg of PF-03654746 + 60 mg of fexofenadine, 60 mg of fexofenadine + 120 mg of pseudoephedrine, and placebo with at least 10 days between study periods.
The effect of a single dose of study medication on minimum nasal cross-sectional area and nasal volume after ragweed challenge was measured with acoustic rhinometry, and participants reported nasal symptoms of congestion, itching, and rhinorrhea on a 0- to 5-point scale.
The 10 mg of PF-03654746 plus fexofenadine dose significantly decreased the nasal congestion symptoms compared with placebo (-0.7; p=0.011), the investigators report. It also showed statistically significant effects on all other symptom scores versus placebo.
The effect of the 1 mg of PF-03654746 plus fexofenadine dose was also significant versus placebo for itching, rhinorrhea, and sneeze count, the data indicate. Fexofenadine/pseudoephedrine versus placebo had a statistically significant effect for rhinorrhea and sneeze count.
“In combination with fexofenadine, single doses of PF-03654746 caused a reduction in allergen-induced nasal symptoms,” the researchers conclude. “H3 receptor antagonism might be a novel therapeutic strategy to further explore in patients with allergic rhinitis.”