title: Effects of fexofenadine on the early response to nasal allergen challenge.
abstract: BACKGROUND
  Previous studies using nasal allergen challenge models have shown that terfenadine, an H1 antihistamine, inhibits histamine release during the early response to allergen provocation. Fexofenadine, the active metabolite of terfenadine, has strong H1-antihistaminic activity and no cardiac effects. Clinical studies have documented the efficacy of fexofenadine in the treatment of allergic rhinitis.
  
  
  OBJECTIVE
  To determine whether fexofenadine, like terfenadine, inhibits histamine and tryptase release during the early allergic response.
  
  
  METHODS
  Randomized, double blind, placebo-controlled, two-way crossover study in 20 subjects with seasonal allergic rhinitis, out of their allergy season (median age 27.5 years, 13 males and 7 females). Subjects were medicated with either placebo or fexofenadine 180 mg orally daily for 1 week followed by nasal challenge with allergen. After each challenge, sneezes and nasal symptoms were recorded, and a nasal lavage was obtained for the assay of albumin, an indicator of vascular permeability, and histamine and tryptase, indicators of mast cell degranulation.
  
  
  RESULTS
  When patients were on placebo, allergen challenges led to significant increases in all measured parameters compared with the sham challenges with diluent. Treatment with fexofenadine resulted in inhibition of allergen-induced symptoms and increased vascular permeability, but not the release of histamine and tryptase.
  
  
  CONCLUSIONS
  Fexofenadine is an effective H1 antihistamine, but in contrast to its parent compound, terfenadine, it does not affect the release of the mast cell mediators histamine and tryptase.
authors.affiliation: Section of Otolaryngology-Head and Neck Surgery, The Pritzker School of Medicine, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Frances T
authors.initials: FT
authors.lastname: Allocco
authors.forename: Virginia
authors.initials: V
authors.lastname: Votypka
authors.forename: Marcy
authors.initials: M
authors.lastname: deTineo
authors.forename: Robert M
authors.initials: RM
authors.lastname: Naclerio
authors.forename: Fuad M
authors.initials: FM
authors.lastname: Baroody
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens; D015415:Biomarkers; D002199:Capillary Permeability / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006634:Histamine H1 Antagonists / Q000737:chemistry / Q000494:pharmacology*; D006636:Histamine Release / Q000187:drug effects*; D006801:Humans; D008297:Male; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism; D008875:Middle Aged; D015394:Molecular Structure; D009296:Nasal Cavity; D009299:Nasal Provocation Tests; D011537:Pruritus / Q000209:etiology; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy; D012697:Serine Endopeptidases / Q000378:metabolism*; D012709:Serum Albumin / Q000032:analysis; D012912:Sneezing; D013329:Structure-Activity Relationship; D016593:Terfenadine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D007507:Therapeutic Irrigation; D053802:Tryptases
chemical_list: D000485:Allergens; D015415:Biomarkers; D006634:Histamine H1 Antagonists; D012709:Serum Albumin; D016593:Terfenadine; C093230:fexofenadine; D012697:Serine Endopeptidases; D053802:Tryptases