How does an adrenergic crisis differ from other hypertensive emergencies?
These patients present with acutely increased alpha-adrenergic tone, typically because of:
• Excess catecholamines or their congeners
• Abrupt withdrawal of oral alpha-2 adrenergic agonists (e.g., clonidine, guanabenz, guanfacine)
• Ingestion of cocaine, amphetamines
• Ingestion of tyramine-rich foodstuffs during monoamine oxidase inhibitor therapy
These patients are usually treated successfully with phentolamine (or the alpha-2 agonist that they stopped abruptly), although some physicians prefer labetalol, which also has beta-adrenergic inhibitory effects.
