Effect of azelastine on the seasonal increase in non-specific bronchial responsiveness to methacholine in pollen allergic patients. A randomized, double-blind placebo-controlled, crossover study.

Azelastine, a phthalazinone derivative, is a new potent, long acting, orally active anti-allergic compound with particularly strong H1-histamine receptor antagonistic effects which has been proven to possess in vitro and in vivo a number of anti-inflammatory properties. The aim of the present study was to investigate whether azelastine would be able to prevent and/or reverse the seasonal increase in non-specific bronchial responsiveness to methacholine in pollen allergic patients. Twelve atopic patients (5 males, mean age 31 years), skin positive exclusively to grass and/or Parietaria pollen extract, with rhinitis and mild asthma occurring in the spring for at least two years previously, were studied. After a 2 week run-in period, oral azelastine, 4 mg twice daily, or placebo, was given for 2 weeks from the start of the pollen season, according to a randomized, double-blind design. After 2 weeks, the treatments were crossed over. During both the run-in and study periods, patients recorded rhinitis and asthma symptoms, additional antihistamine and bronchodilator drugs taken and peak expiratory flow measurements. A methacholine inhalation test was carried out on four occasions in each patient: before the run-in period, before the start of the treatment, and at the end of the two 2 week treatment periods. Azelastine significantly reduced rhinitis symptoms and the need for antihistamine drugs, whereas asthmatic symptoms, use of bronchodilator drugs, peak flow recordings and bronchial responsiveness to methacholine were unaffected by the treatment. Compliance level and adverse side-effects were not significantly different between active treatment and placebo. In the final subjective evaluation of the two treatments, eight out of 12 patients preferred azelastine.(ABSTRACT TRUNCATED AT 250 WORDS)