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CARDIOVASCULAR SYSTEM › PERIPHERAL VASODILATORS › PERIPHERAL VASODILATORS › Imidazoline derivatives
phentolamine
C04AB01
Forms & Strengths
- Injectable solution: 5 mg/mL
Adult Dosing
- Diagnosis of pheochromocytoma (blocking test): 5 mg IV or IM
- Prevention/treatment of dermal necrosis from norepinephrine extravasation: 5 to 10 mg in 10 mL saline infiltrate subcutaneously
- Hypertensive crisis: 5 mg IV repeated as needed
Pediatric Dosing
- Diagnosis of pheochromocytoma: 0.1 mg/kg IV or IM (maximum 5 mg)
- Prevention/treatment of norepinephrine extravasation: 0.1 to 0.2 mg/kg (maximum 10 mg total) infiltrated locally
Indications
- Diagnosis of pheochromocytoma
- Prevention and treatment of dermal necrosis and sloughing following intravenous extravasation of norepinephrine or dopamine
- Management of hypertensive crises caused by sympathomimetic amine excess
Mechanism of Action
- Competitive alpha-1 and alpha-2 adrenergic receptor antagonist
- Produces vasodilation and decreases peripheral vascular resistance through blockade of circulating epinephrine and norepinephrine
Contraindications
- Hypersensitivity to phentolamine or other alpha-adrenergic blocking agents
- History of myocardial infarction
- Coronary artery disease, angina, or other evidence of ischemic heart disease
Adverse Reactions
- Hypotension and reflex tachycardia
- Cardiac arrhythmias and angina
- Dizziness, flushing, and weakness
- Nausea, vomiting, and diarrhea
Drug Interactions
- Additive hypotensive effects with antihypertensive agents and alcohol
- Antagonism of the pressor effects of sympathomimetic agents such as epinephrine and norepinephrine
Curated Content: Needs Vetting Before Put to Clinical Use