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Irreversible Non-Selective Alpha Adrenoceptor Antagonist — Phaeochromocytoma Pre-operative Preparation

Phenoxybenzamine

Brand names: Dibenyline

Phenoxybenzamine is a non-selective, irreversible alpha-adrenoceptor antagonist used mainly to control hypertension and sweating in phaeochromocytoma, including preoperative preparation.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It irreversibly blocks alpha-adrenoceptors, producing long-lasting vasodilatation and counteracting the effects of circulating catecholamines.

Prescribing in practice

  • Marked postural hypotension and reflex tachycardia are expected, so it is started under close supervision and adequate alpha blockade must be established before any beta blocker is added to avoid unopposed alpha effects.
  • Intravenous administration must be given slowly with the patient lying down and blood pressure monitored, owing to the risk of severe hypotension.
  • Use with caution in cerebrovascular or ischaemic heart disease and in renal impairment.

Monitoring

Monitor lying and standing blood pressure and heart rate closely, especially during initiation and dose titration.

Counselling the patient

  • Dizziness on standing, a fast heartbeat and nasal stuffiness are common.
  • Stand up slowly and report fainting or marked light-headedness.
  • Do not stop the medicine suddenly without medical advice.

Evidence & guidelines

Phenoxybenzamine is an established agent for preoperative alpha blockade in phaeochromocytoma, with beta blockade added only after adequate alpha blockade.

Reference: Endocrine Society Phaeochromocytoma Guidelines 2014; UK Phaeochromocytoma Guidelines (Specialist Advisory Committee); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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