Two double-blind, double-dummy, randomized, crossover studies were performed in 8 asthmatic patients to evaluate β₂-adrenoceptor selectivity and potency of broxaterol compared to salbutamol. By oral route, a study with cumulatively increasing doses (total dose broxaterol 1.675 mg and salbutamol 26 mg) showed that as a bronchodilator broxaterol was 12–16 times more potent than salbutamol. The same potency difference was seen for an increase of heart rate and decrease of diastolic blood pressure, indicating that the clinical selectivity for β₂-adrenoceptors is equal for the two drugs. One study with cumulatively increasing doses of broxaterol and salbutamol (total dose 1.5 mg for both) showed that with the inhaled route, broxaterol was somewhat less potent than salbutamol with respect to bronchodilation. Side effects, increase of heart rate and tremor were considerably less pronounced by the inhaled route as compared to the same bronchodilatory effect given by the oral route.