Cardiorespiratory activitirs of 3-formylamino-4-hydroxy-alpha-(n-1-methyl-2-p-methoxyphenethylaminomethyl)-benzylalcohol-hemifumarate(BD 40A) and some other beta-adrenoceptor stimulants in conscious guinea pigs.

The beta-stimulant activity of 3-formylamino-4-hydroxy-alpha-(N-1-methoxyphenethylaminomethyl)-benzylalcohol-hemifumarate (BD 40A) was compared with those of isoproterenol, orciprenaline, trimetoquinol and salbutamol in conscious guinea pigs. Bronchodilator effects of BD 40A were most potent among five agonists by s.c., oral and aerosol administration, and were lasting by oral and aerosol administration. BD 40A was similar to isoproterenol, more potent than trimetoquinol, orciprenaline and salbutamol in increasing heart rate by s.c. route. The cardiostimulating effect of BD 40A was more potent than that of isoproterenol, trimetoquinol and salbutamol orally. However, the order of bronchoselectivity (ratio between ED30 beats/min vs. ED50) in conscious guinea pigs was salbutamol greater than BD 40A = trimetoquinol greater than orciprenaline greater than isoproterenol by s.c. administration, and by oral administration the order was BD 40A = salbutamol greater than trimetoquinol = isoproterenol. Orciprenaline showed no beta-stimulating effect in guinea pigs orally. In guinea pigs, BD 40A, like salbutamol, seems to be a beta2-adrenoceptor stimulant.