Phentolamine

Phentolamine

Management of Extravasation Injuries

• Please note that there are 2 protocols
  • Management of Non-vasoactive medications: Hyaluronidase
  • Management of vasoactive medications: Phentolamine

Indication

• The management of IV extravasations (leakage of an IV fluid out of a vein and into surrounding tissue)
• For the management of extravasation due to vasoactive medications (eg. dobutamine, dopamine, epinephrine, norepinephrine, phenylephrine)

Pharmacology

• Competitively blocks alpha - adrenergic receptors, thereby producing brief antagonism of circulating epinephrine and norepinephrine
• This causes relaxation of vascular smooth muscle and the development of a hyperemic response (increase of blood flow)
• Phentolamine also stimulates beta adrenergic receptors and produces a positive inotropic (force of contraction) and chronotropic (rate) effect on the heart

Side Effects

• CDV: hypotension, tachycardia, cardiac arrhythmias
• GI: vomiting, diarrhea,
• Other: nasal congestion

Warning

• Use with caution in patients with renal impairment or gastritis

Dose

• Add 1.8 mL sterile water to 0.2 mL of 5 mg/mL phentolamine
  • Final Concentration: =1 mg/2mL or =0.5 mg/mL
• Infiltrate the area of extravasation with multiple small injections of the 0.5 mg/mL solution
• Use a 27g or smaller needle and change needles between each skin entry
• Do not inject a volume such that swelling of the area occurs
• It has been suggested that a dose of 0.1 mg/kg (ie. 0.2 mL/kg of the 0.5 mg/mL solution) not be exceeded

Monitoring

• Blanching should reverse immediately
• Monitor site of extravasation closely; additional injections of phentolamine may be necessary

Treatment of Overdose

• Main clinical manifestations are hypotension, tachycardia, cardiac stimulation, and arrhythmias
• Norepinephrine (initial dose: 0.05 to 0.1 mcg/kg/min, then cautiously titrated in a continuous IV infusion to a maximum of 1 to 2 mcg/kg/min), is the pharmacological antagonist
• Do not use epinephrine; this may cause a further fall in blood pressure

Supplied As

• 5mg/mL, 1mL ampoule
• Kept in refrigerator
• Trade name is "Rogitine(R)"