Two New β2-Adrenoceptor Agonists, D-2343 and QH 25, Studied in Asthmatic Patients

Two new beta 2-adrenoceptor agonists, D-2343 and QH 25, have been studied in asthmatic patients. Animal experiments indicated less effect on skeletal muscle than on bronchial muscle. D-2343 (four i.v. cumulatively increasing doses, 0.21--6.3 micrograms kg-1 min-1) and i.v. terbutaline (four cumulative doses 0.07--2.1 micrograms kg-1 min-1) were single-blindly compared in a randomized crossover study in eight asthmatics. It was shown that D-2343 is an effective beta 2-adrenoceptor agonist with 5--6 times lower potency than terbutaline. The tremor-inducing effect of D-2343 was the same as that of terbutaline, when the same degree of bronchodilation was obtained. The effect of QH 25 (0.25, 0.75 and 2.25 mg cumulatively) administered orally, was single-blindly compared with the effect of oral salbutamol (2, 6 and 18 mg) in a randomized crossover study in eight asthmatics. QH 25 was shown to be an effective beta 2-adrenoceptor stimulant about 12 times more potent than salbutamol. The tremor-inducing capacity was the same as for salbutamol when equipotent bronchodilating doses were studied.