ANTITUSSIVE EFFECT OF AZELASTINE HYDROCHLORIDE IN PATIENTS WITH BRONCHIAL-ASTHMA

To investigate the efficacy of azelastine hydrochloride (azelastine, C AS 79307-93-0, Azeptin(R)) in suppressing cough, 22 bronchial asthma p atients complaining mainly of cough were given the drug for four weeks . Peak flow rates (PEFR), pulmonary function tests, capsaicin cough th reshold, and bronchial hyperresponsiveness were compared pre-and post- administration. After four-week's administration of azelastine (2 mg t wice daily), cough decreased as demonstrated in a significant progress ive improvement of cough points. The morning PEFR (1/min) was improved significantly at one week and two weeks postadministration. Changes w ere from 434 +/- 26.4 pre-administration to 461 +/- 25.8 at Week 1 (p < 0.05), 462 +/- 26.7 at Week 2 (p < 0.05), 452 +/- 22.5 at Week 3, an d 462 +/- 20.8 at Week 4. The evening PEFR (1/min) showed 439 +/- 22.2 pre-administraiton, 454 +/- 21.4 at Week 1, 464 +/- 22.4 at Week 2, 4 57 +/- 19.3 at Week 3 and 467 +/- 17.8 at Week 4, improvement being si gnificant at Week 1 (p < 0.05). Regarding pulmonary function tests, no significant changes were observed. FVC (liter), FEV1 (liter), and FEV 1/FVC (%) were 3.45 +/- 0.86, 2.68 +/- 0.52, and 83.6 +/- 5.93 pre-adm inistration; and 3.48 +/- 0.21, 2.72 +/- 0.65, and 84.1 +/- 6.21 post- administration, respectively. The capsaicin cough threshold [Ccap (mu mol/l)] showed significant improvement, changing from 5.95 (0.016-50.0 ) pre-administration to 19.7 (0.08-50.0) post-administration (p < 0.05 ). Conversely, an index of bronchial hyperresponsiveness, D-min (mg/dl ; U), showed no significant changes (14.9 +/- 5.2 vs. 19.7 +/- 5.3). T hese results suggest that azelastine inhibits cough in patients with b ronchial asthma by increasing the level of the cough threshold without changing bronchial hyperresponsiveness.