Administration for Extravasation:

1. Using a 10 mL syringe, withdraw 2 mL (10 mg) of phentolamine and add 8 mL of Normal Saline (0.9% saline) to make a 1 mg/mL phentolamine solution.
2. Disconnect IV tubing from the hub of the catheter (if not already done) and inject 1 mL of the phentolamine solution. Then, remove the catheter.
3. Using a hypodermic needle, inject 0.5 to 1 mL of the remaining phentolamine subcutaneously in multiple sites around the perimeter of the infiltrated area (at least 5 injections with one half inch between the sites.  
4. It may not be necessary to use all the prepared phentolamine.
5. The amount of the solution used will vary with the size of the area of infiltrated tissue.
6. Erythema, pain and hypotension may occur.If the dose is effective, normal skin color should return to blanched area within one hour.

• UpToDate
• FDA Package Inserts