BRONCHODILATOR REVERSIBILITY TO LOW AND HIGH-DOSES OF TERBUTALINE ANDIPRATROPIUM BROMIDE IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

Background-There is uncertainty regarding the use of monotherapy or co mbination therapy with beta2 agonists and anticholinergic drugs in pat ients with chronic obstructive pulmonary disease (COPD). The measureme nt of forced expiratory volume in one second (FEV1) or relaxed vital c apacity (RVC) in the assessment of reversibility in these patients has also caused considerable debate. Methods-Twenty seven patients with C OPD were evaluated on two occasions. Patients received the following t reatments in sequence: (sequence 1) low dose terbutaline 500 mug, high dose terbutaline 5000 mug, low dose ipratropium 40 mug, high dose ipr atropium 200 mug; (sequence 2) low dose ipratropium 40 mug, high dose ipratropium 200 mug, low dose terbutaline 500 mug, high dose terbutali ne 5000 mug. RVC, FEV, and FVC were measured at baseline and 30 minute s after successive treatments. Results-Values for FEV, at baseline on the first and second study days were not significantly different: 0.90 (0.87-0.93) 1 v 0.90 (0.87-0.93) 1. Likewise, baseline' values for RV C and FVC were not different. The number of patients showing a greater than 330 ml overall improvement in RVC was 20 of 27 for sequence 1 an d 22 of 27 for sequence 2; similar trends were observed for FEV, and F VC. For all three parameters there was a significant difference betwee n mean responses to low and high doses of terbutaline when the latter was given as the first drug in sequence 1. When ipratropium was given first in sequence 2 there was, however, no significant improvement wit h high dose terbutaline over and above the response to low dose terbut aline. The latter effect was more noticeable with RVC than with either FEV, or FVC. The total bronchodilator response at the end of each seq uence was similar whether ipratropium was given first or second. Concl usions-The measurement of RVC, FEV1, and FVC were equally effective at picking up those patients who had a significant overall bronchodilato r response to combined therapy with inhaled beta2 agonist and antichol inergic medication. There was no significant benefit of adding a highe r dose of terbutaline when ipratropium bromide had been given previous ly, particularly when using RVC as the parameter of response.