The protective effect of
broxaterol against bronchial hyperresponsiveness has been assessed in several double-blind randomized controlled studies in stable asthmatic patients. In three cross-over studies,
broxaterol (400 micrograms by
metered dose inhaler) has been shown to significantly reduce
methacholine responsiveness 30, 60 and 120 min after dosing. The protective effect was similar to that obtained with
terbutaline (500 micrograms), but there was a trend toward a higher activity of
fenoterol (400 micrograms), even if counterbalanced by a more frequent occurrence of side effects.
Broxaterol 0.5 mg by oral route provided a significant greater protection against the
exercise-induced bronchospasm than 0.02 mg of
clenbuterol and a placebo. Also in children,
broxaterol 0.25 mg as
nebulizer solution significantly prevented
exercise-induced bronchospasm versus placebo, and this effect was seen to be associated with an improvement in maximal working capacity. Prevention of
bronchospasm following 3 or 4 consecutive challenges with inhaled distilled water mist was demonstrated after oral and
aerosol administration of
broxaterol. This effect was not significantly different from that observed with
salbutamol, if administered by
aerosol. Finally, in a cross-over placebo-controlled study,
broxaterol (400 micrograms by
aerosol) significantly inhibited
allergen-induced immediate bronchoconstriction. These data suggest that
broxaterol represents a new valid alternative to the most effective beta 2-stimulants now commonly used.