Name: PHENTOLAMINE (RogitineR)
Classification: alpha antagonist; vasodilator
  • alpha blockade in pheochromocytoma (used with a beta blocker)
  • antidote for extravasation of alpha stimulants
  • antihypertensive agent
  • afterload reduction
  • useful to treat hypertension in MAO-I overdose
  • Bolus dose: 
    • 1-5mg IV direct
  • Infusion
    • 6mg - 40 mg/hour and titrate to blood pressure. Doses up to 120 mg/hour have been used for severe hypertension.
  • Antidote for vasoconstrictor extravasation: 
    • 5-15mg in 10 mL NS infiltrated into the area of extravasation as soon as possible.  Treatment may be beneficial up to 12 hours post extravasation injury.
    • administer initial dose into interstitial catheter prior to removal to direct phentolamine into area of infiltration
    • anticipate need for increased sympathomimetic therapy and/or volume therapy
Administration: IV Infusion:
300mg/500mLdextrose 5%, normal saline 0.9% or Ringer's Lactate
  • should be weaned off
  • treat hypovolemia concurrently with initiation of drug therapy
  • For pheochromocytoma blockade - initiate phentolamine prior to commencing beta blockade; beta blockade may increase peripheral vasoconstriction and worsen hypertension
Adverse Effects:
  • hypotension
  • hypovolemia
  • tachycardias
  • arrhythmias
  • increased gastric acid secretion
  • tachyphylaxis may occur 
Drug Interactions:
  • phentolamine + alpha adrenergic agents = decreased alpha effects
Monitoring Therapy:
  • IV site
  • blood pressure
  • continuous heart rate and ECG rhythm
  • urine output
  • lactate
Adult Critical Care Protocol:
  • May be administered IV direct or by IV infusion by a nurse in Adult Critical Care.
  • May be titrated by a nurse in Adult Critical Care.
  • Administration by central venous access device is preferred.
  • Patient requires placement of an arterial line to monitor BP.
  • Continuous infusions must be administered by infusion device and the pump library must be enabled.
  • Should not be infused via the proximal injectate port (blue) of a pulmonary artery catheter. If this is the only available central venous line, it may be administered through the proximal injectate port but thermodilution cardiac output measurements must not be measured during infusion).

Lynne Kelly, Pharmacist, CCTC
Brenda Morgan, Clinical Nurse Specialist, CCTC
Last Update: November 15, 2019