Salbutamol and Isoproterenol

In a double-blind crossover trial in patients with asthma, similar initial bronchodilator activity was achieved with inhalations of salbutamol (100 μg), a new beta-adrenergic receptor-stimulating drug, and isoproterenol (500 μg), but the duration of action was longer with salbutamol. Heart rate did not increase with salbutamol but showed a small rise with isoproterenol. Normal subjects were given five times this dose of each drug. Salbutamol produced a small mean increase in heart rate (4 beats a minute) and no palpitation, whereas isoproterenol produced a large mean increase in heart rate (33 beats a minute) and pronounced palpitation. For comparable bronchodilator activity salbutamol appears to cause much less cardiovascular beta-receptor stimulation than isoproterenol, and it may prove to be more useful in the treatment of asthma.