Plasma propranolol levels in the quaniitative assessment of beta-adrenergic blockade in man
Abstract
Plasma propranolol levels associated with reductions in endogenous and exogenous cardiac beta-stimulation were determined in normal people. The levels associated with a given degree of blockade of exercise-induced tachycardia were about three times greater after intravenous administration than after oral administration. This shows that an active metabolite of propranolol is formed only after the drug is taken by mouth. The greatest reduction in the tachycardia of strenuous exercise was associated with plasma levels of 40 ng./ml. with oral administration and 100 ng./ml. with intravenously administered propranolol.The effect on isoprenaline-induced tachycardia following intravenously administered propranolol showed that the dose ratio for isoprenaline was about 30 with plasma levels of 100 ng./ml. and 10 with levels of 10-20 ng./ml. These plasma levels give 100% and 20-30% blockade of exercise-induced tachycardia. These findings suggest that some of the therapeutic effects of propranolol may be unrelated to beta-adrenergic blockade.
References
Citations
A comparison of the actions of ICI66082 and propranolol on cardiac and peripheral beta-adrenoceptors
Efficacy of propranolol in the control of exercise-induced or augmented ventricular ectopic activity
Bronchial and cardiac beta-adrenoceptor blockade--a comparison of atenolol, acebutolol and labetalol
Concentration-effect relationships with FM 24: a new long acting beta-adrenergic receptor antagonist
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