Comparative potency of intravenous penbutolol and propranolol in man.

A study on the comparative potency of intravenously administered penbutolol, a new non-selective beta adrenoceptor antagonist, on the resting and post-exercise heart rate and rate-pressure product was carried out in 5 normal human subjects. The effects produced by 0.1, 0.2 and 0.3 mg of penbutolol and of 0.025 mg/kg (mean dose 1.28 mg) of propranolol was recorded. The dose of penbutolol producing an effect equivalent to that of propranolol was calculating from the log dose-response curve of penbutolol. In these tests, penbutolol was 7.90 and 7.66 times more potent than propranolol on a weight to weight basis. Penbutolol was well tolerated and no side-effects were observed.