Sympathomimetic and cardiodepressant effects of acebutolol, oxprenolol, pindolol, and propranolol. A comparative study on changes in hemodynamics, contractility, heart rate, and AV-conduction time at therapeutic doses.
The present study was undertaken in order to obtain further informations on non-beta-antiadrenergic properties of the four beta-sympatholytic agents acebutolol, oxprenolol, pindolol, and propranolol. Standardized experiments were performed using a chronically reserpinized canine preparation for the assessment of dose-response curves of changes in hemodynamics, left ventricular contractility, heart rate, AV-conduction time, and myocardial oxygen consumption especially at therapeutic doses. Our results show that acebutolol and oxprenolol, at doses clinically recommended, exert moderate positive inotropic effects but do not influence heart rate significantly. Pindolol has a strong both positive chronotropic and inotropic efficacy, even at small therapeutic doses. Propranolol produces neither chronotropic nor inotropic effects. In contrast to the literature acebutolol exerts direct cardiodepression at doses clinically used, whereas oxprenolol, pindolol, at propranolol have no direct cardiodepressant properties at those doses. Thus the relationship between the dose requirements for chronotropic and inotropic sympathomimetic effects differs for each beta-sympatholytic agents, and in may prove impossible to get an order of intrinsic sympathomimetic potency of beta-blockers comparing dose-response curves of heart rate changes only. As shown in the case of acebutolol, direct cardiodepression of beta-sympatholytic agents may occur at therapeutic doses.
D000070:Acebutolol / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D000889:Anti-Arrhythmia Agents; D001283:Atrioventricular Node / Q000187:drug effects; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007231:Infant, Newborn; D009200:Myocardial Contraction / Q000187:drug effects; D010096:Oxprenolol / Q000494:pharmacology; D010869:Pindolol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013566:Sympathomimetics
D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D013566:Sympathomimetics; D010096:Oxprenolol; D000070:Acebutolol; D011433:Propranolol; D010869:Pindolol