Intravenous practolol (0.3 to 0.6 mg/kg) significantly reduced the response of heart rate, cardiac index, pre-ejection period, and tension time index to adrenergic stimuli in normal volunteers.
RCT (n=9)
Latin squares
Cardiospecific beta blockade by practolol was studied in 9 normal volunteers on three separate occasions. Three adrenergic stimuli (epinephrine, 0.1 mcg/kg/min, isoproterenol, 0.025 mcg/kg/min, and exercise, 50 watts) and three intravenous doses of practolol were randomly paired in three Latin squares. Observations of heart rate, arterial blood pressure, cardiac output, and systolic time intervals were obtained under baseline control conditions; during beta adrenergic stimulation; after a recovery period of 30 minutes; under resting conditions; after administration of practolol; and during repeated beta adrenergic stimulation to assess the effect of practolol as a cardioselective beta adrenergic blocking agent. Under basal conditions, blood levels of practolol (0.37, 0.89, and 1.86 mcg/ml) resulted in physiologically unimportant changes in the parameters measured. Dose levels of 0.3 to 0.6 mg/kg of practolol administered intravenously significantly reduced the response of heart rate, cardiac index, pre‐ejection period, and tension time index to at least two of the three adrenergic stimuli used. There was no evidence for dimct myocardial depression by practolol although the direct inotropic effect of catecholamine infusion was significantly attenuated by the highest doses of practolol.
Thompson et al. (1974) conducted an RCT in Healthy volunteers (n=9). Practolol vs. Baseline control conditions was evaluated on Response of heart rate, cardiac index, pre-ejection period, and tension time index to adrenergic stimuli. Intravenous practolol (0.3 to 0.6 mg/kg) significantly reduced the response of heart rate, cardiac index, pre-ejection period, and tension time index to adrenergic stimuli in normal volunteers.