Effect of terfenadine and ipratropium bromide on ultrasonically nebulized distilled water-induced asthma

Inhalation of ultrasonically nebulized distilled water was used to evaluate non-specific bronchial reactivity and to investigate nonimmunologically mediated asthma. Release of histamine and other mediators from mast cells and stimulation of lung irritant receptors are mechanisms that may be involved in nebulized distilled water-induced bronchoconstriction. To investigate the contribution of these mechanisms the effect of terfenadine and ipratropium bromide on the bronchial response to this stimulus was assessed. A total of 30 asthmatics (mean 28.7 years) were submitted on three different days to distilled water challenge with or without prior treatment with oral terfenadine or inhaled aerosolized ipratropium bromide. The decrease in forced expiratory volume in 1 s induced by the same dose of distilled water was significantly (P less than 0.001) reduced from 35.6 +/- 15.8% to 19.5 +/- 16% with terfenadine and to 23.9 +/- 19.7% with ipratropium bromide. The results suggest that histamine release and reflex bronchoconstriction are mechanisms involved in asthma induced by ultrasonically nebulized distilled water.