Phenoxybenzamine
DIBENZYLINE
What it isIrreversible non-selective alpha antagonist; preoperative blockade in phaeochromocytoma.
Why this oneIrreversible blockade cannot be overcome by a catecholamine surge, which is exactly what is needed during tumor handling.
What limits itReflex tachycardia and profound orthostasis; a beta blocker must not be started first. The effect persists for days after stopping.
FDA-approved for
- pheochromocytoma (~1953)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Pheochromocytoma (BP/sweating control) | Adult | 10 mg BID | 20-40 mg BID-TID |
Titration Increase dose every other day per BP/response
Renal Undefined
Hepatic Undefined
Instructions
- Long-term use not recommended (carcinogenicity concern)
Contraindications
- Conditions where a fall in blood pressure is undesirable
Cautions
- Postural hypotension and reflex tachycardia
- Nasal congestion, miosis
Adverse reactions
- Postural hypotension, tachycardia
- Nasal congestion, miosis, inhibition of ejaculation
- Drowsiness, fatigue, GI irritation
Pregnancy Animal reproduction studies not performed; use only if clearly needed.
Lactation Undefined
NO BOXED WARNINGS
Principal riskReflex tachycardia and profound orthostasis
Cost, est. cash$10–$500/month
Generic entry2012
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
Mechanism of action: Phenoxybenzamine ballicule
