Effects of practolol on pressor responses to noxious stimuli in hypertensive patients

The effect of practolol, a ß‐adrenergic blocker, on the cardiovascular response to noxious stimuli was studied in 10 patients with mild to moderate hypertension. Two oral dose levels of 400 and 800 mg. per day were employed in a short‐term study that was carefully monitored by blood levels of the drug; the effects were compared to that of an identical placebo administered in a double blind fashion. Results indicated no change in the resting blood pressure or pulse rate in these patients at either dose level. Similarly, the pressor responses to ischemic pain and cold pressor testing were not affected. However, responses of the pulse rate to the stimuli and to 60 degree tilt were Significantly dampened. Hemodynamic studies were done in 3 patients and revealed no consistent patterns of change in the relationships between cardiac output and peripheral resistance during the pressor responses. No adverse symptomatic or systemic side effects were noted at either dose level. The results confirmed the relative ineffectiveness of this compound as a sole agent in treating hypertensive patients but suggest it may be of some value as a supplement to vasodilator compounds.