TABLE 4

Potency, onset, and duration of action of β-adrenergic receptor agonists in isolated spontaneous tone human bronchi

EC₅₀ values were calculated from percentages of relaxation obtained from cumulative concentration-response curves in preparations at spontaneous tone. Onset and duration of action were determined by applying a single concentration of agonist that produced a 40 to 60% of effect with respect to theophylline. Onset of action was defined as the time spanning from agonist addition to the attainment of 50% of the maximal relaxation produced by the concentration added. Duration of action was defined as the time spanning from agonist washout to the attainment of 50% recovery from the relaxation produced by the concentration added. Potency data are reported as mean and confidence interval (95% CI). Onset and duration of action data are reported as mean ± S.E.M. n/p experiments involve the number of rings (n) and the number of patients (p).