Role of broxaterol in bronchial hyperresponsiveness.

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.