title: Histamine skin test reactivity following single and multiple doses of azelastine nasal spray in patients with seasonal allergic rhinitis.
abstract: OBJECTIVE
  To determine whether azelastine nasal spray suppresses the dermal response to epicutaneous histamine in allergic patients and the duration of suppression after azelastine use is discontinued.
  
  
  METHODS
  Seventy-eight patients with seasonal allergic rhinitis were entered into this randomized, double-blind, parallel-group, placebo-controlled study. Patients received either azelastine nasal spray (2 sprays per nostril twice daily) or placebo nasal spray for 14 days. Skin tests were performed 5 hours after the first dose of study drugs to determine the effect of a single dose of azelastine nasal spray on the wheal-and-flare response to histamine. At the end of the 14-day treatment period, skin tests were performed 5 hours after the last dose of study drugs and at 24-hour intervals thereafter, until each patient's wheal-and-flare response to histamine (1.0 and 5.0 mg/mL) returned to within 20% of baseline values.
  
  
  RESULTS
  A single dose of azelastine nasal spray did not significantly alter the wheal-and-flare response to histamine. The wheal response was within 20% of the baseline value in 82% and 88% (1.0 and 5.0 mg/mL of histamine, respectively) of the patients 5 hours after discontinuing 14 days of treatment with azelastine nasal spray. Wheal responses were within 20% of baseline values 48 hours after treatment was discontinued, whereas flare responses returned to within 20% of baseline within 48 hours in 92% of the patients.
  
  
  CONCLUSIONS
  Azelastine nasal spray should be discontinued for at least 48 hours before beginning allergy skin test procedures.
authors.affiliation: Colorado Allergy & Asthma Centers, PC, Denver, Colorado 80230, USA. ds.pearlman@coloradoallergy.com
authors.forename: David S
authors.initials: DS
authors.lastname: Pearlman
authors.forename: Jay
authors.initials: J
authors.lastname: Grossman
authors.forename: Eli O
authors.initials: EO
authors.lastname: Meltzer
mesh_terms: D000281:Administration, Intranasal; D000293:Adolescent; D000328:Adult; D018926:Anti-Allergic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002648:Child; D004311:Double-Blind Method; D005260:Female; D006632:Histamine; D006801:Humans; D008297:Male; D008875:Middle Aged; D010793:Phthalazines / Q000008:administration & dosage / Q000627:therapeutic use*; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy*; D012882:Skin Tests; D015206:Southwestern United States; D013997:Time Factors
chemical_list: D018926:Anti-Allergic Agents; D010793:Phthalazines; D006632:Histamine; C020976:azelastine