Hypertensive Encephalopathy Medication

Pharmacologic agents selected for use in hypertensive encephalopathy should have few or no CNS adverse effects. Avoid agents such as clonidine, reserpine, and methyldopa. Although the clinical impact has not been determined, diazoxide is avoided because of the impact of decreased cerebral blood flow. If neurological deterioration worsens with therapy, reconsider the extent of blood pressure lowering or consider alternate diagnoses.

Labetalol provides a steady consistent drop in blood pressure without compromising cerebral blood flow. Labetalol is frequently used as initial therapy. Because of nonselective beta-blocking properties, it should be avoided in severe reactive airways disease and cardiogenic shock.

Nitroglycerin has been used to provide a rapid reduction in blood pressure complicating myocardial ischemia. The reduction in blood pressure may be severe and can cause further complications due to venodilatory effects in volume-contracted individuals. Nitroprusside and hydralazine pose a theoretical risk of intracranial shunting of blood. Thus, these agents should be avoided in patients suspected of having increased intracranial pressure (ICP) because they may cause intracerebral shunting of blood, which increases ICP. An increasing number of authorities are considering labetalol, nifedipine, and esmolol as the preferred initial agent.

Trimethaphan camsylate is used to reduce the shearing force in the presence of aortic dissection. Hydralazine has a limited role, owing to reflex tachycardia, and it should not be used in patients with suspected coronary artery disease.

Class Summary

These agents are used to reduce blood pressure.

Labetalol (Normodyne)

Competitive and selective alpha1-blocker and nonselective beta-blocker with predominantly beta effects at low doses. Onset of action is 5 min, with half-life of 5.5 h. Provides a steady, consistent drop in BP without compromising cerebral blood flow.

Nicardipine (Cardene)

Calcium channel blocker. Potent rapid onset of action, ease of titration, and lack of toxic metabolites. Effective but limited reported experience in hypertensive encephalopathy.

Esmolol (Brevibloc)

Ultra — short-acting agent that selectively blocks beta 1 receptors with little or no effect on beta 2 receptor types. Particularly useful in patients with elevated arterial pressure, especially if surgery is planned. Shown to reduce episodes of chest pain and clinical cardiac events compared with placebo. Can be discontinued abruptly if necessary.

Useful in patients at risk for experiencing complications from beta-blockade; particularly those with reactive airway disease, mild-moderate LV dysfunction, and/or peripheral vascular disease. Short half-life of 8 min allows for titration to desired effect and quick discontinuation if needed.

Nitroprusside sodium (Nitropress)

Decreases systemic vascular resistance via direct dilatation of arterioles and veins. Should be avoided in patients suspected of having increased ICP. May cause intracerebral shunting of blood, increasing ICP.

Trimethaphan camsylate (Arfonad)

A ganglionic blocking agent primarily used in aortic dissection. Reduces heart rate and left ventricular ejection rate, thus lowering shearing force.

Phentolamine (Regitine)

Alpha1- and alpha2-adrenergic blocking agent that blocks circulating epinephrine and norepinephrine action, reducing hypertension that results from catecholamine effects on the alpha receptors.

Nitroglycerin IV (Nitro-Bid)

Provides arteriolar dilation and venodilation. Used in emergencies involving myocardial ischemia due to the dilatory effects of nitroglycerin on coronary arteries.

Hydralazine (Hydrea)

Direct arteriolar dilator. Limited role because of reflex tachycardia causing increased cardiac oxygen demand. Should be avoided in patients suspected of having increased intracranial pressure.