Vasodilators direct Hydralazine Initial 10 mg via slow IV infusion (maximum initial dose 20 mg); repeat every 4 6 h as needed. BP begins to decrease within 10 30 min, and the fall lasts 2 4 h. Unpredictability of response and prolonged duration of action do not make hydralazine a desirable first-line agent for acute treatment in most patients. Adrenergic receptor selective antagonist Esmolol Loading dose 500 1000 mcg/kg/min over 1 min followed by a 50-mcg/kg/min infusion. For additional dosing, the bolus dose is repeated and the infusion increased in 50-mcg/kg/min increments as needed to a maximum of 200 mcg/kg/min. Contraindicated in patients with concurrent beta-blocker therapy, bradycardia, or decompensated HF. Monitor for bradycardia. May worsen HF. Higher doses may block beta2 receptors and impact lung function in reactive airway disease. Adrenergic blockers combined and nonselective beta receptor antagonist Labetalol Initial 0.3 1.0-mg/kg dose (maximum 20 mg) slow IV injection every 10 min or 0.4 1.0-mg/kg/h IV infusion up to 3 mg/kg/h. Adjust rate up to total cumulative dose of 300 mg. This dose can be repeated every 4 6 h. Contraindicated in reactive airways disease or chronic obstructive pulmonary disease. Especially useful in hyperadrenergic syndromes. May worsen HF and should not be given in patients with second- or third-degree heart block or bradycardia. Adrenergic blockers nonselective alpha receptor antagonist Phentolamine IV bolus dose 5 mg. Additional bolus doses every 10 min as needed to lower BP to target. Used in hypertensive emergencies induced by catecholamine excess (pheochromocytoma, interactions between monamine oxidase inhibitors and other drugs or food, cocaine toxicity, amphetamine overdose, or clonidine withdrawal). -receptor selective agonist Fenoldopam Initial 0.1 0.3 mcg/kg/min; may be increased in increments of 0.05 0.1 mcg/kg/min every 15 min until target BP is reached. Maximum infusion rate 1.6 mcg/ kg/min. 