The response pattern of patients with chronic airway obstruction to bronchodilators

To investigate the response pattern of patients with chronic airway obstruction (CAO) to bronchodilators, 128 subjects consisting of 80 men and 48 women with a mean age of 52.6 years were randomly tested with three inhalant bronchodilators: a non-selective beta-agonist (isoproterenol), a beta 2-selective agonist (terbutaline) and an anticholinergics (ipratropium) plus placebo. All patients had a baseline FEV/FVC of less than 65% and their clinical diagnosis were classified as either COPD or bronchial asthma according to the criteria of the ACCP-ATS Joint Committee on Pulmonary Nomenclature. The drugs were delivered to the patient via a metered dose inhaler (MDI) using the conventional inhalation technique. Spirometry was measured at regular intervals with a computerized pulmonary function analyzer CHESTAC-65(Japan). A more than 15% increase in FEV1 and/or FVC after treatment was regarded as responsive. While 108 patients were tested with a single drug, the remaining 20 patients were tested sequentially with terbutaline, ipratropium and placebo in a randomized cross-over manner for studying additivity. Our results showed that the response rates of asthmatic patients to isoproterenol, terbutaline and ipratropium were 50%, 87% and 67%, respectively. Only 27% of COPD patients responded to isoproterenol and 60% to terbutaline. On the other hand, ipratropium possessed a 61% response rate in the treatment of COPD and showed a bronchodilator effect independent to that of terbutaline. Combined use of both drugs resulted in additional improvement. Once patients responded to the drugs, apparent changes in FEV1 and/or FVC occurred within 30 minutes and reached the maximum usually at 60 minutes post-inhalation.(ABSTRACT TRUNCATED AT 250 WORDS)