title: Onset-of-action for antihistamine and decongestant combinations during an outdoor challenge.
abstract: 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.
authors.affiliation: Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA. jgeorgitis@wfubmc.edu
authors.forename: J W
authors.initials: JW
authors.lastname: Georgitis
authors.forename: E O
authors.initials: EO
authors.lastname: Meltzer
authors.forename: M
authors.initials: M
authors.lastname: Kaliner
authors.forename: J
authors.initials: J
authors.lastname: Weiler
authors.forename: R
authors.initials: R
authors.lastname: Berkowitz
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000276:immunology; D000485:Allergens / Q000276:immunology; D018926:Anti-Allergic Agents / Q000627:therapeutic use; D004311:Double-Blind Method; D004338:Drug Combinations; D004809:Ephedrine / Q000627:therapeutic use*; D005260:Female; D006634:Histamine H1 Antagonists / Q000627:therapeutic use*; D006801:Humans; D017336:Loratadine / Q000627:therapeutic use*; D008297:Male; D014663:Nasal Decongestants / Q000627:therapeutic use*; D011058:Pollen / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy* / Q000209:etiology; D013997:Time Factors; D014311:Triprolidine / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D000393:Air Pollutants; D000485:Allergens; D018926:Anti-Allergic Agents; D004338:Drug Combinations; D006634:Histamine H1 Antagonists; D014663:Nasal Decongestants; D014311:Triprolidine; D017336:Loratadine; C043648:acrivastine; D004809:Ephedrine