Adrenergic crisis in hypertensive emergencies

Adrenergic crisis is most commonly due to stimulant use (eg cocaine, amfetamines) or a phaeochromocytoma.

Phentolamine is the most appropriate drug to reduce BP in adrenergic crisis¹. Consider using an intravenous dose of hydralazine as an interim measure until phentolamine is available. If phentolamine is not available, consider using an intravenous infusion of sodium nitroprusside. See Hypertensive emergency for dosage information.

Benzodiazepines can be a useful adjunct to BP-lowering therapy in adrenergic crisis, as they can reduce catecholamine-induced tachycardia and hypertension. The anxiolytic and sedative properties of benzodiazepines are beneficial in an anxious patient or a patient whose behaviour is affected by stimulant use. For dosage information, see Pharmacological treatment of behavioural emergencies.

Monotherapy with a beta blocker is contraindicated in adrenergic crisis, as unopposed alpha receptor–mediated vasoconstriction can cause an extreme rise in BP. A short-acting beta blocker such as esmolol may be considered for a patient with significant tachycardia and ongoing hypertension, but should only be started when sufficient alpha blockade is in place (eg with phentolamine). Avoid labetalol (a beta blocker that also has alpha blocking effects), as its safety in adrenergic crisis is not established.