Phentolamine

Administration
  • Type: Alpha 1 Blocker; Antidote, Extravasation; Antihypertensive
  • Routes of Administration: IV, IM
  • Common Trade Names: OraVerse

Adult Dosing
  • Pheochromocytomectomy adjunct: 5mg IM/IV q2-4h PRN
    • Start: 1-2h preop
  • Extravasation (norepinephrine-associated): 5-10mg injected into affected area x1
    • Start: within 12h of extravasation
  • Hypertensive crisis: 5mg IM/IV q2-4h PRN

Pediatric Dosing
  • Pheochromocytomectomy adjunct: 1mg IM/IV q2-4h PRN
    • Start: 1-2h preop

Special Populations
  • Pregnancy Risk Factor: C

Renal Dosing
  • No dosing adjustments

Hepatic Dosing
  • No dosing adjustments

Contraindications
  • Hypersensitivity to phentolamine or components
  • MI
  • CAD
  • Angina
  • Caution if PUD

Adverse Reactions

Serious
  • MI
  • stroke
  • hypotension, severe
  • arrhythmias
  • PUD
  • priapism

Common
  • tachycardia
  • weakness
  • dizziness
  • flushing
  • orthostatic hypotension
  • nasal congestion
  • nausea
  • vomiting
  • diarrhea

Pharmacology
  • Half-life: 19 minutes
  • Metabolism: Urine
  • Excretion: CYP450

Mechanism of Action
  • α antagonist

References

<Epocrates, UpToDate>

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