A comparative study of the activity of beta-adrenoceptor antagonists in man.

1. In healthy subjects the plasma concentration of unchanged drug, heart rate response to excerise and attenuation of isoprenaline tachycardia were maximal at one hour after ingestion of a range of doses of propranolol, oxprenolol, practolol, tolamolol, atenolol and metoprolol. 2. There was a within-drug relationship between plasma concentration of unchanged drug and the attenuation of exercise and iosprenaline tachycardia. There was no similar between-drug relationship. 3. There was a similar exponential relationship between oral dose and reduction of exercise tachycardia for all six drugs. 4. The linear relationship between oral dose and antagonism of infused isoprenaline was significantly greater for oxprenolol and propranolol than for the other four drugs. 5. "Cardioselective" activity was the only ancillary pharmacological property which differentiated the activity of these drugs in normal subjects.