Rapid reduction of blood pressure with acute oral labetalol.

1 The effect of acute oral administration of labetalol on intra-arterial pressures in a group of ten hypertensive patients has been evaluated. 2 A single dose of 200 mg labetalol produced a significant reduction in systolic and diastolic pressures within 1 h of administration. 3 Within 24 h of initial administration, 200 mg three times daily produced a significant reduction in ambulant arterial levels of systolic pressure for 21 h and diastolic pressure for 14 h in the day. 4 Acute therapy lowered resting levels but there was no significant reduction in systolic pressure during either isometric or dynamic exercise. 5 Acute therapy was not associated with any significant postural hypotension.