Evaluation of onset of bronchodilating effect by interruption of the air flow method.

The speed of onset of the bronchodilating effect of ibuterol, a derivative of terbutaline, was measured by the method of air flow interruptions, which enables an almost continuous study of lung resistance before and after the administration of a bronchodilator. In the double-blind comparison between ibuterol and placebo, the onset of action of the new beta 2-agonist has been shown to take place within 30-45 sec. This indicates that ibuterol is a bronchodilator with rapid onset of action.