Onset-of-action for antihistamine and decongestant combinations during an outdoor challenge.

Author(s): Georgitis JW, Meltzer EO, Kaliner M, Weiler J, Berkowitz R

Affiliation(s): Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA. jgeorgitis@wfubmc.edu

Publication date & source: 2000-04, Ann Allergy Asthma Immunol., 84(4):451-9.

Publication type: Clinical Trial; Multicenter Study; Randomized Controlled Trial

BACKGROUND: Medications containing a combination antihistamine-decongestant are commonly used for allergic rhinitis yet onset-of-action comparisons for symptom relief after a single dose have not been performed. OBJECTIVE: To determine the onset of symptom relief and efficacy of antihistamine-decongestant medications (acrivastine-pseudoephedrine and loratadine-pseudoephedrine) compared with placebo in an outdoor park. METHODS: This study was conducted during the spring of 1997 using a double-blind, placebo-controlled design. Patients completed baseline rhinitis symptom diaries from 7:30 to 9:30 AM. Subjects with qualifying symptom scores received one dose of either acrivastine-pseudoephedrine, loratadine-pseudoephedrine, or placebo at 10:00 AM. Symptom diaries were recorded for the next 4 hours. RESULTS: Of 593 patients randomized to treatment, 592 were included in efficacy analysis. Acrivastine-pseudoephedrine and loratadine-pseudoephedrine demonstrated a mean onset-of-action by 45 and 30 minutes respectively for total symptom and rhinitis symptom scores for the five sites. Onset-of-action for nasal congestion scores was 45 minutes for both medications. Sites having higher pollen exposure (>100 pollen grains over 6 hours) demonstrated a difference between the antihistamine combinations: acrivastine-pseudoephedrine had an onset of action at 45 minutes for total symptom and rhinitis symptom scores, and 15 minutes for nasal congestion scores whereas loratadine-pseudoephedrine had onset-of-action for nasal congestion score of 105 minutes but failed to reach significance at any timepoint for total symptom and rhinitis symptom scores. CONCLUSIONS: Both antihistamine-decongestant combinations demonstrate an onset-of-action within 60 minutes of administration but under conditions of higher pollen exposure, the acrivastine combination was more effective for total symptoms, rhinitis symptoms, and nasal congestion with an onset-of-action within 45 minutes for rhinitis symptoms and 15 minutes for congestion.