Labetalol infusion in hypertensive emergencies.

The antihypertensive effects of labetalol infusion (2 mg/min; maximal dose 150 mg) were evaluated in 22 subjects requiring rapid lowering of blood pressure because of severe hypertension, a hypertensive crisis after surgery, or before angiographic examination. Overall systolic and diastolic blood pressures were reduced from 201 +/- 4 to 164 +/- 4 mm Hg and from 123 +/- 3 to 107 +/- 3 mm Hg, respectively. By the end of the infusion, diastolic blood pressure in 16 (73%) subjects was lowered to less than or equal to 110 mm Hg. No adverse effects were encountered, but one subject had a transitory hypotensive episode that did not require treatment. Intravenous labetalol appears effective and well tolerated in the control of blood pressure in hypertensive emergencies.