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Alpha-1 Adrenoceptor Antagonist — Hypertension / Raynaud's / BPH

Doxazosin

Brand names: Cardura, Doxadura

Doxazosin is a long-acting selective alpha-1 adrenoceptor antagonist used for hypertension, often as add-on therapy, and for symptomatic benign prostatic hyperplasia.

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 selectively blocks postsynaptic alpha-1 adrenoceptors on vascular smooth muscle and the prostate, producing vasodilatation and reduced bladder outflow resistance.

Prescribing in practice

  • First-dose and postural hypotension can cause collapse, so treatment is started at a low dose, ideally at bedtime, and patients warned to rise slowly.
  • It can interact additively with other antihypertensives and with phosphodiesterase-5 inhibitors to lower blood pressure.
  • Intra-operative floppy iris syndrome can complicate cataract surgery, so the ophthalmologist should be told.

Monitoring

Monitor blood pressure, including for postural drop, after initiation and dose changes, and review for dizziness, oedema and symptomatic response.

Counselling the patient

  • Take the first dose at bedtime and stand up slowly to avoid dizziness.
  • Tell your eye surgeon you take this drug before cataract surgery.
  • Report fainting, marked dizziness or ankle swelling.

Evidence & guidelines

The ALLHAT trial showed the doxazosin arm had more heart failure than a thiazide-type diuretic, which is why it is generally reserved as add-on rather than first-line antihypertensive therapy.

Reference: ALLHAT Trial; MHRA Drug Safety Update (IFIS); BSR/BHPR Raynaud's Guidelines; 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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