- 10 mg/1 ml ampules (subcutaneous)
- 5 mg lyophilized powder (subcutaneous)

Executive Summary

(July 2, 2023)

Phentolamine is a vasodilator used to prevent tissue necrosis caused by extravasated catecholamine infusions (epinephrine, norepinephrine, dopamine, etc). Available in the US. Limited stock in Canada. Unavailable in Chile. 

Adult dose for vasopressor extravasation:
5-10 mg diluted in 10-20 ml of NaCl 0.9% subcutaneous immediately after extravasation (use within 12 hours). 

Adult dose

Adult dose for injection site vasopressor extravasation

Phentolamine 5 to 10 mg in 10 ml of normal saline,  subcutaneous within 12 hours into the area of extravasation. 

Pediatric dose

Pediatric dose for injection site vasopressor extravasation

Mechanism of Action and Usage

Mechanism of Action



Renal, hepatic, or other adjustments

No adjustments required. 

Dosage Forms and brand names


The following issues of concern are related mostly to  endovenous administration of phentolamine. Consider that subcutaneous use in extravasation is intended to cause local effects rather than systemic effects. The following issues of concern are related to IV administration. 

Pregnancy and Lactation

Consider that subcutaneous use in extravasation is intended to cause local effects rather than systemic effects, with an hypothetical low risk for the fetus or infant. 


Alpha-adrenergic block of relatively short duration. Also direct but less marked positive inotropic and chronotropic effects. The pharmacokinetics of phentolamine are largely unknown. 

Following specifications are not applicable to subdermic administration:


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