||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:
- 0.1mg - 2mg/min (start at lowest dose and titrate to blood pressure). Doses up to 2 mg/min 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; may be effective up to 12 hours post extravasation of vasoconstrictor
- 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
300mg/500mL D5W, NS RL
- 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
- increased gastric acid secretion
- tachyphylaxis may occur
- phentolamine + alpha adrenergic agents = decreased alpha effects
- HR, ECG
- urine output
- cardiac index
- SVRI, PVRI
- arterial lactate
- May be administered by IV infusion or IV direct by an approved nurse in CCTC.
- May be titrated by an approved nurse in CCTC.
- Preferable to administer via a central line.
- Continuous infusion must be administered via an infusion pump.
- Should not be infused via proximal injectate port (blue) of the Swan Ganz catheter.
- Patient requires placement of an arterial line to monitor BP.