Phentolamine (Regitine, OraVerse)

Pheochromocytoma - Drug of choice for intraoperative hypertensive crises during tumor manipulation, given as 1-5 mg IV boluses.

Extravasation rescue - Antidote for alpha-agonist (norepinephrine, phenylephrine, dopamine) extravasation; 5-10 mg in 10 mL saline infiltrated into the affected area.

Rapid brief effect - Onset 1-2 min with short duration; titrate by repeat boluses or infusion.

Unopposed alpha caution - Reflex tachycardia is common, but never give a beta-blocker before adequate alpha blockade in pheochromocytoma.

Excessive effect - Treat hypotension with fluids, Trendelenburg, and norepinephrine; avoid epinephrine (epinephrine reversal causes paradoxical hypotension).

Drug Interactions - Potentiates other antihypertensives; classic epinephrine reversal (paradoxical hypotension when epinephrine given after alpha blockade).

Pediatric Implications - Extravasation dose 0.05-0.1 mg/kg (max 5 mg); pheochromocytoma dosing is weight-based.

Obstetric Implications - Limited data; used for pheochromocytoma crisis in pregnancy when clearly needed.

Absolute:

Recent myocardial infarction

Coronary insufficiency, angina

Relative:

Peptic ulcer disease

Pre-existing hypotension

Caution:

Elderly

Cerebrovascular disease

Pheochromocytoma: 1-5 mg IV; pediatric 0.05-0.1 mg/kg (max 5 mg).

Extravasation: 5-10 mg in 10 mL normal saline, subcutaneous infiltration of affected area.

5 mg IM (pheochromocytoma preoperative preparation)

Competitive nonselective antagonism of alpha-1 and alpha-2 adrenergic receptors, producing vasodilation.

Hepatic

Renal

Reconstitute lyophilized powder to 5 mg/mL.

Also marketed as OraVerse for reversal of dental soft-tissue anesthesia.