title: Twenty-four hours of activity of cetirizine and fexofenadine in the skin.
abstract: BACKGROUND
  Cetirizine and fexofenadine, the active metabolite of terfenadine, are powerful and well-tolerated H1 receptor antagonists effective in the treatment of skin and nose atopic diseases.
  
  
  OBJECTIVE
  We have compared the pharmacodynamic activity of the two antihistamines at therapeutic dosages, cetirizine at 10 mg and fexofenadine at 120 mg and 180 mg, on histamine-induced skin reactivity during a 24-hour period after single intake.
  
  
  METHODS
  Twenty-six healthy volunteers participated in a randomized, double-blind, crossover, placebo-controlled study. The areas of wheal and flare induced by histamine (100 mg/mL) administered by prick test were measured at 0, 0.5, 1, 2, 4, 6, 8, 10, 12, and 24 hours postdose. Statistical analysis of the areas under the time-response curves was performed by a Friedman's ANOVA followed by a Wilcoxon test and Bonferroni's correction.
  
  
  RESULTS
  The three active treatments clearly inhibited the wheal and flare areas throughout the 24-hour period compared with placebo. Maximal inhibition occurred at 4 hours postdose. Between 4 and 24 hours postdose, the time course of inhibition by cetirizine differed significantly (P < 0.001) from that by fexofenadine at either dose, which did not differ from each other. At 24 hours, fexofenadine inhibited <40% of the skin reaction, whereas cetirizine reduced 60% of the wheal. The duration of effect, considered as the time for wheal to be inhibited by at least 70%, also significantly favored cetirizine (19 hours) compared with fexofenadine (9.3 and 8.5 hours for 180 and 120 mg, respectively; P < 0.001). Consistency of activity was evaluated by the frequency of total inhibition of the wheal (> or =95%). Consistency was observed in 26 of 26 participants for cetirizine, 21 of 26 for fexofenadine, 180 mg, and 10 of 26 for fexofenadine, 120 mg (P < 0.001), suggesting better consistency for cetirizine. There was no serious adverse event.
  
  
  CONCLUSIONS
  Our study clearly shows better duration of action and consistency of the antihistaminic activity of cetirizine compared with fexofenadine (120 and 180 mg) in the histamine-induced skin reaction during a 24-hour period.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, H pitaux Universitaires, Strasbourg, France.
authors.forename: A
authors.initials: A
authors.lastname: Purohit
authors.forename: C
authors.initials: C
authors.lastname: Duvernelle
authors.forename: M
authors.initials: M
authors.lastname: Melac
authors.forename: G
authors.initials: G
authors.lastname: Pauli
authors.forename: N
authors.initials: N
authors.lastname: Frossard
mesh_terms: D000293:Adolescent; D000328:Adult; D018926:Anti-Allergic Agents / Q000009:adverse effects / Q000494:pharmacology*; D017332:Cetirizine / Q000009:adverse effects / Q000494:pharmacology*; D018592:Cross-Over Studies; D003876:Dermatitis, Atopic / Q000517:prevention & control; D004311:Double-Blind Method; D004341:Drug Evaluation; D005260:Female; D006632:Histamine; D006634:Histamine H1 Antagonists / Q000009:adverse effects / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012220:Rhinitis / Q000517:prevention & control; D012867:Skin / Q000187:drug effects; D012882:Skin Tests; D016593:Terfenadine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D018926:Anti-Allergic Agents; D006634:Histamine H1 Antagonists; D016593:Terfenadine; D006632:Histamine; C093230:fexofenadine; D017332:Cetirizine