title: Investigation of the anti-allergic activity of azelastine on the immediate and late-phase reactions to allergens and histamine using telethermography.
abstract: BACKGROUND
  Due to the interest in azelastine's diverse modes of action, this study investigated its effects on immediate and late-phase cutaneous allergic reactions using visual methods and telethermography.
  
  
  OBJECTIVE
  The aim of the study was to investigate the effect of azelastine on the immediate and late-phase skin reactions using both planimetric evaluation of weal and erythema and a telethermographic technique.
  
  
  METHODS
  The study was a double-blind crossover study; medication consisted of one tablet per day for 7 days of either placebo or azelastine 4 mg. Eight allergic patients were assessed on five occasions: prior to treatment, at the end of the first 7-day treatment, after a 21-day washout period, following the second 7-day treatment period and finally following a 2-6 week washout period. Skin prick tests with timothy grass and intradermal tests with Alternaria allergens were performed on the patients' back. In addition, patients were tested with intradermal histamine as a positive control. Surfaces of weal, erythema and infiltration were calculated using computerized planimetry at 0, 20, 40 and 60 min, and 3, 6 and 8 h. Thermographic images were recorded and the thermographic area and the increase in average temperature (DeltaT) were calculated.
  
  
  RESULTS
  The coefficient of variation within baseline reactions ranged from 3 to 32% for weal and erythema and from 5 to 25% for thermographically recorded reactions. The stronger the reaction, the more constant the baseline was. Treatment with azelastine (4 mg/os once daily) inhibited immediate reactions to allergens by 65% (range 55-74) and to histamine by 68% (range 47-82). The late-phase reactions to allergens were less well defined and showed larger individual differences in the degree of inhibition caused by azelastine, they were inhibited by 49% (range 32-67). Late-phase reactions to histamine were less intense and could only be detected with thermography; only thermographic units showed a decrease (26%) in response to azelastine.
  
  
  CONCLUSIONS
  This study has confirmed azelastine's histamine-blocking activity. In addition, the late-phase results suggest that azelastine has anti-inflammatory activity. The reproducibility and sensitivity of the thermographic results confirm the usefulness of this technique in immunopharmacology.
authors.affiliation: Institute for Clinical Immunology, Inselspital, University of Bern, Switzerland.
authors.forename: A L
authors.initials: AL
authors.lastname: De Weck
authors.forename: T
authors.initials: T
authors.lastname: Derer
authors.forename: M
authors.initials: M
authors.lastname: Bähre
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology; D000528:Alternaria / Q000276:immunology; D018926:Anti-Allergic Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy; D018592:Cross-Over Studies; D003876:Dermatitis, Atopic / Q000188:drug therapy / Q000473:pathology; D004311:Double-Blind Method; D005260:Female; D006634:Histamine H1 Antagonists / Q000627:therapeutic use*; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000188:drug therapy* / Q000473:pathology; D006969:Hypersensitivity, Immediate / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D010793:Phthalazines / Q000627:therapeutic use*; D006109:Poaceae / Q000276:immunology; D015203:Reproducibility of Results; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy; D012867:Skin / Q000276:immunology / Q000473:pathology; D012882:Skin Tests; D013817:Thermography / Q000379:methods*
chemical_list: D000485:Allergens; D018926:Anti-Allergic Agents; D006634:Histamine H1 Antagonists; D010793:Phthalazines; C020976:azelastine