Non-Selective Alpha Adrenoceptor Antagonist — Vasopressor Extravasation / Phaeochromocytoma
Pregnancy: Use with caution — limited data; use if clearly necessary
Phentolamine
Brand names: Rogitine
Adult dose
Dose: Vasopressor extravasation: 5–10 mg in 10 mL normal saline — infiltrate SC into affected area within 12 hours; Phaeochromocytoma crisis: 2–5 mg IV bolus, repeat as needed; Pre-operative: 2–5 mg IV 1–2 hours before surgery
Route: Subcutaneous infiltration (extravasation) or IV (phaeochromocytoma)
Frequency: Single infiltration (extravasation); repeat IV doses as needed (phaeochromocytoma crisis)
Max: 10 mg per infiltration; titrated by BP response in phaeochromocytoma
Extravasation: infiltrate with fine needle in multiple small aliquots throughout affected area — erythema should resolve within 1 hour confirming adequate reversal. Must be performed within 12 hours of extravasation (ideal <6 hours). Phaeochromocytoma: phenoxybenzamine preferred pre-operatively for sustained blockade.
Paediatric dose
Dose: 0.1 mg/kg SC mg/kg
Route: SC infiltration or IV
Frequency: Single dose (extravasation); titrated (phaeochromocytoma)
Max: 5 mg per dose
BNFc: used in paediatric vasopressor extravasation and phaeochromocytoma
Dose adjustments
Renal
No specific dose adjustment
Hepatic
Use with caution
Paediatric weight-based calculator
BNFc: used in paediatric vasopressor extravasation and phaeochromocytoma
Clinical pearls
- Critical for vasopressor extravasation (noradrenaline, dopamine, adrenaline, metaraminol) — tissue necrosis develops within hours; phentolamine infiltration is the standard antidote
- Time is tissue: must infiltrate within 12 hours — erythema/blanching resolves in 1 hour if effective
- Epinephrine reversal paradox: if epinephrine given for phentolamine-induced hypotension, the beta-2 vasodilation is unmasked — use noradrenaline instead
- For phaeochromocytoma perioperative management: phenoxybenzamine (irreversible) for sustained pre-op blockade is preferred; phentolamine used for acute hypertensive crises intraoperatively
- Hyaluronidase can be co-administered for extravasation to enhance SC spread of phentolamine
Contraindications
- Hypotension
- Coronary artery disease (reflex tachycardia worsens ischaemia)
- History of MI
Side effects
- Hypotension
- Reflex tachycardia
- Flushing
- Nasal congestion
- Nausea
- Diarrhoea
- Angina (in CAD patients)
Interactions
- Antihypertensives — additive hypotension
- Epinephrine — paradoxical hypotension if given after phentolamine (epinephrine's beta effect unopposed)
- Sympathomimetics — effect reversed
Monitoring
- Blood pressure (continuous for IV use)
- Tissue perfusion and skin colour at extravasation site
- Heart rate
Reference: BNFc; BNF 90; UK Medicines Information (UKMi) Extravasation Guidelines; Endocrine Society Phaeochromocytoma Guidelines 2014. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.