Efficacy of fexofenadine in the prophylactic control of cat allergen-induced allergic rhinitis

Background: To date, it is unknown whether fexofenadine mitigates the worsening of symptoms induced by the cat allergen Felis domesticus allergen 1. Objective: To determine the effects of a single dose of fexofenadine hydrochloride, 180 mg, in preventing and controlling cat allergen-induced allergic rhinitis symptoms using the cat room challenge model. Methods: This single-center, randomized, double-blind, placebo-controlled, 2-way crossover study consisted of a screening visit, 1 or 2 qualifying visits, and 2 treatment periods separated by a mean +/- SD washout period of 14 +/- 3 days. Patients were randomized to treatment sequence 1 (placebo followed by fexofenadine) or sequence 2 (fexofenadine followed by placebo). Baseline end points were obtained before study drug administration, and allergen challenges were initiated 1(1/2) hours after dosing. The primary end point was the change from predose baseline in the total symptom score (sum of rhinorrhea, itchy nose/palate/ throat, sneezing, and itchy/watery/red eyes) after 30 minutes of allergen exposure compared with placebo. Results: Of 211 patients screened, 66 were randomized and 63 completed the study. Mean change in the total symptom score from predose baseline was significantly less with fexofenadine compared with placebo 30 minutes after initiation of the cat allergen challenge (2 hours after dosing) (P =.03). The overall incidence of treatment-emergent adverse events was low and comparable for both groups. Conclusion: Prophylactic treatment with a single dose of fexofenadine hydrochloride, 180 mg, significantly mitigated the worsening of allergic rhinitis symptoms induced by exposure to cat allergen compared with placebo use.