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

Background-There is uncertainty regarding the use of monotherapy or combination therapy with beta2 agonists and anticholinergic drugs in patients with chronic obstructive pulmonary disease (COPD). The measurement of forced expiratory volume in one second (FEV1) or relaxed vital capacity (RVC) in the assessment of reversibility in these patients has also caused considerable debate.

Methods-Twenty seven patients with COPD were evaluated on two occasions. Patients received the following treatments in sequence: (sequence 1) low dose terbutaline 500 mug, high dose terbutaline 5000 mug, low dose ipratropium 40 mug, high dose ipratropium 200 mug; (sequence 2) low dose ipratropium 40 mug, high dose ipratropium 200 mug, low dose terbutaline 500 mug, high dose terbutaline 5000 mug. RVC, FEV, and FVC were measured at baseline and 30 minutes 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 RVC 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 and 22 of 27 for sequence 2; similar trends were observed for FEV, and FVC. For all three parameters there was a significant difference between 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 with high dose terbutaline over and above the response to low dose terbutaline. The latter effect was more noticeable with RVC than with either FEV, or FVC. The total bronchodilator response at the end of each sequence was similar whether ipratropium was given first or second. Conclusions-The measurement of RVC, FEV1, and FVC were equally effective at picking up those patients who had a significant overall bronchodilator response to combined therapy with inhaled beta2 agonist and anticholinergic medication. There was no significant benefit of adding a higher dose of terbutaline when ipratropium bromide had been given previously, particularly when using RVC as the parameter of response.