Comparison of protective effect of bronchodilators in COPD

Protective effect of bronchodilators against methacholine-induced constriction was shown in asthmatic patients, but many COPD patients have bronchial hyperresponsiveness (BHR) also. Aim: To evaluate the change of BHR level in COPD patients after a single dose of tiotropium bromide (TB) and formoterol. Methods: 34 COPD II outpatients with initial BHR of meanage of 61 yrs were studied. BHR was to quantify in methacholine challenge. Criteria of positive BHR was provocative dose (PD20)<0,471 mg. The BHR level was analyzed initially and post 1h after 18 mcg TB (1-st group, n=15) and 12 mcg formoterol (2-nd group, n=19). Results: Among 34 patients a high level of BHR (PD20 0,04-0,22 mg) and low (PD20 0,23-0,47 mg) in 13 and 7 patients accordingly. Pre-bronchodilators PD20 medians were comparable in both groups: 0,047 mg for the 1-st and 0,064 mg for the 2-nd group (p=0,29). BHR levels post-bronchodilators 1h were significantly less in both groups. Thus, PD20 medians increased in 4,4 times after formoterol (p=0,008) and in 7,5 times after TB (p= 0,005). The number of negative tests (PD20>0,471 mg) in the 1-st group was more than in the 2-nd: 8 patients after TB vs 4 patients after formoterol (p=0,055). ![Figure][1] Conclusion: Long-acting bronchodilators – TB and formoterol demonstrate early bronchoprotective effect after single administration. TB has shown a more protective effect against methacholine-induced bronchoconstriction than formoterol in COPD patients. [1]: pending:yes