1. The effect of 4.4 mg
azelastine administered orally on airway responsiveness, skin prick testing, daily peak expiratory flow rates and symptoms of
asthma was compared with placebo in
a 7 week double-blind, parallel group study of 24 patients with extrinsic
asthma. The study was in two parts: a 2 week assessment period, during which all patients received placebo
tablets but recorded daily peak flow rates (PEFRs) and symptoms, preceding the 7 week double-blind comparison. 2.
Azelastine, 4.4 mg, significantly decreased airway responsiveness to
histamine compared with placebo both after a single dose (P less than 0.001), and following 7 weeks continuous treatment (P less than 0.02). Airway responsiveness to
methacholine was not altered by administration of
azelastine compared with placebo. 3. Skin prick test weal diameters to both
allergen and
histamine were significantly reduced after both a single dose and following 7 weeks continuous
therapy treatment with
azelastine. 4. There was a significant improvement in both the mean of the morning and the evening peak flow rates recorded during the last week compared with the first week of the study in the group receiving 4.4 mg of
azelastine twice daily compared with placebo. Scores for wheeze were significantly reduced during the final 3 weeks of the study in patients receiving
azelastine compared both with those receiving placebo and with the first week of the study (P less than 0.05, P less than 0.01). Consumption of inhaled
bronchodilators fell significantly during the study in the group receiving
azelastine therapy (P less than 0.05); no such fall occurred in the placebo treated patients. 5. A bitter
metallic taste was reported by 58% of patients who received
azelastine therapy.