title: Comparison of four beta-blockers as assessed by 24-hour ECG recording.
abstract: beta-Blockers are used as if they were equivalent. With ECG recordings in 42 patients we investigated the effect on sinus heart rate of four beta-blockers given at three successive daily doses. Heart rate was dose-dependently decreased by all drugs except acebutolol, the effect of which decreased at a higher dosage. The maximal effects of metoprolol, nadolol, and propranolol were similar but the drugs differed in potency (dosage producing 50% of maximal effect, calculated from the dose-effect relationships; nadolol, 0.3 mg/day; metoprolol, 120 mg/day; propranolol, 47 mg/day). Similar relationships were found with drug plasma concentrations (concentration producing 50% of maximal effect: nadolol, 3.5 ng/ml; metoprolol, 21 ng/ml; propranolol, 36 ng/ml) and with supine or upright heart rates and blood pressures. However, the drugs were not equivalent: In addition to its greater potency, nadolol differed from propranolol and metoprolol in the slope of its dose-response curve. We conclude that beta-blockers can be compared by ECG recordings and that nadolol is different from the other beta-blockers without intrinsic sympathomimetic activity.
mesh_terms: D000070:Acebutolol / Q000097:blood / Q000494:pharmacology*; D000284:Administration, Oral; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004341:Drug Evaluation; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000097:blood / Q000494:pharmacology*; D008875:Middle Aged; D009248:Nadolol; D011412:Propanolamines / Q000097:blood / Q000494:pharmacology*; D011433:Propranolol / Q000097:blood / Q000494:pharmacology*; D011897:Random Allocation
chemical_list: D011412:Propanolamines; D009248:Nadolol; D000070:Acebutolol; D011433:Propranolol; D008790:Metoprolol