The role of calcium entry blockers in hypertensive emergencies.

This review focuses on the potential use of the calcium antagonists diltiazem, nifedipine, and verapamil in the treatment of hypertensive emergencies. Prompt reduction of blood pressure can be achieved after either intravenous administration of diltiazem or verapamil or sublingual/oral administration of nifedipine. Effects on cardiac hemodynamics with these drugs are variable. Effects on the kidney are predictable; administration is associated with prompt diuresis and natriuresis. Effects on the cerebral circulation are more complex; although cerebral vasodilation may occur, the potential exists for uneven cerebral perfusion and an increase in intracranial pressure. Precipitous decreases in mean arterial pressure may decrease cerebral blood flow below the lower limit of autoregulation, inducing cerebral ischemia. Because of the complex interaction of these drugs on the heart, kidney, and brain, short-term therapy should be instituted only in the hospital setting, with appropriate supervision and hemodynamic monitoring.