Onset of action, efficacy, and safety of fexofenadine 60 mg/pseudoephedrine 120 mg versus placebo in the Atlanta allergen exposure unit

Background: Second-generation antihistamine-decongestant combinations are often used to treat seasonal allergies. However, onset of action and efficacy data for these agents in a controlled setting are limited. Objective: Determine onset of action of fexofenadine-pseudoephedrine (Allegra-D, Aventis, Bridgewater, NJ) for treating moderate-to-severe seasonal allergies in an allergen exposure unit. Methods: This single-dose, double-blind, placebo-controlled study was conducted during the fall ragweed allergy season. Qualifying subjects attended one to two priming visits; those with sufficient symptom scores returned for treatment and were initially exposed to ragweed pollen for 90 minutes. Symptomatic subjects received fexofenadine-pseudoephedrine or placebo and recorded symptoms for 6 hours postdose. Efficacy variables were major symptom complex (MSC; sneezes, itchy nose, runny nose, watery eyes, itchy eyes, itchy ears/throat, stuffy nose), total symptom complex (nose blows, sniffles, postnasal drip, cough, plus all MSC symptoms), and all individual symptoms as well as headache. Onset of action for each efficacy variable was calculated as the earliest time at which a consistent, significant decrease was seen for fexofenadine-pseudoephedrine versus placebo. Results: Of 571 screened subjects, 298 were randomized. Onset of relief for fexofenadine-pseudoephedrine (n = 148) was 45 minutes postdose (MSC, P = 0.0127; total symptom complex, P = 0.0380). All individual symptoms were reduced to a greater extent with fexofenadine-pseudoephedrine than with placebo (P < 0.05, not adjusted for multiple comparisons). Decrease in headache with fexofenadine-pseudoephedrine versus placebo began 45 minutes postdose (P = 0.0425). Incidence of treatment-related adverse events was 1.4% for fexofenadine-pseudoephedrine and 3.3% for placebo. Conclusions: Fexofenadine-pseudoephedrine was safe and effective in treating a broad range of allergy symptoms, with a rapid onset of action at 45 minutes.