In vitro effect of beta 2-agonists on bacterial killing and superoxide anion (O2-) release from alveolar macrophages of patients with chronic bronchitis

A new class of long-acting beta 2-adrenoceptor agonists has been studied in the last few years. Apparently, they display an important anti-inflammatory activity with an inhibition of different cellular functions. This study was carried out to compare a long-acting beta 2-agonist, formoterol, with a conventional short-acting one, salbutamol, on the release of superoxide anion (O2-) and bacterial killing by alveolar macrophages obtained with bronchoalveolar lavage (BAL) from 20 patients with chronic bronchitis. The O2- production in basal conditions was not affected by beta 2-agonists. On the contrary, after phagocytosis of opsonized zymosan 10(-5) M formoterol significantly affected the phagocytic index (difference between stimulated and basal O2- release): 7.9 +/- 2.0 nM O2-/10(6) AM/10 min vs 16.8 +/- 2.5, p < 0.0007. Bacterial killing was inhibited by the two drugs in a dose-dependent way, but the effect of formoterol was more evident than that of salbutamol. After blocking beta 2-receptors with propranolol, we observed a prevention of the beta 2-agonist effects on both O2- release and bacterial killing. The inhibition of the alveolar macrophage functions considered in this study is evident for both beta 2-agonists, but it is significantly more pronounced for formoterol. Our data can be interpreted as one possible mechanism of the anti-inflammatory effect described for long-acting beta 2-agonists. On the other hand, also a potential suppression of pulmonary antibacterial defenses must not be overlooked, particularly in chronic bronchitis, a disease characterized by recurrent airways infections. Whether current therapeutic dosages are sufficient to achieve anti-inflammatory or microbicidal suppressive effects of clinical relevance has not been demonstrated so far.

Protective effect and duration of action of formoterol aerosol on exercise-induced asthma

The short-term protective effect on exercise-induced asthma (EIA) and the duration of action of formoterol, given by metered dose aerosol at a dose of 24 micrograms, were compared with salbutamol (200 micrograms) and placebo in twelve asthmatic EIA-positive patients in a double-blind, placebo-controlled, three period cross-over study. On each treatment day the patients were given one of the drugs or placebo and two exercise tests were performed at the second and at the eighth hour after dosing. Using a standard procedure, exercise was performed by treadmill in well-controlled environmental conditions. In the first test at 2 h a significant difference relative to placebo (p less than 0.001) at each incremental time after exercise (i.e. 5, 10, 15, 20, 30 min) was obtained with both formoterol and salbutamol, without any significant difference between formoterol and salbutamol. After the eighth hour test formoterol still protected against EIA in comparison to both salbutamol and placebo. The effect of salbutamol at this time was not different from placebo. No adverse effects were reported in any treatment group. Formoterol has a long duration of action in protecting against EIA that persisted for eight hours, removing the need to dose with beta 2-agonist before every exercise.

Protective effect and duration of action of formoterol aerosol on exercise-induced asthma

The short-term protective effect on exercise-induced asthma (EIA) and the duration of action of formoterol, given by metered dose aerosol at a dose of 24 micrograms, were compared with salbutamol (200 micrograms) and placebo in twelve asthmatic EIA-positive patients in a double-blind, placebo-controlled, three period cross-over study. On each treatment day the patients were given one of the drugs or placebo and two exercise tests were performed at the second and at the eighth hour after dosing. Using a standard procedure, exercise was performed by treadmill in well-controlled environmental conditions. In the first test at 2 h a significant difference relative to placebo (p less than 0.001) at each incremental time after exercise (i.e. 5, 10, 15, 20, 30 min) was obtained with both formoterol and salbutamol, without any significant difference between formoterol and salbutamol. After the eighth hour test formoterol still protected against EIA in comparison to both salbutamol and placebo. The effect of salbutamol at this time was not different from placebo. No adverse effects were reported in any treatment group. Formoterol has a long duration of action in protecting against EIA that persisted for eight hours, removing the need to dose with beta 2-agonist before every exercise.