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

Prazosin

Brand names: Hypovase

Prazosin is a selective alpha-1 adrenoceptor antagonist used in hypertension, Raynaud's phenomenon and 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, causing arterial and venous vasodilatation and reducing peripheral vascular resistance.

Prescribing in practice

A pronounced first-dose hypotensive effect with collapse can occur, so the first dose should be low and taken on retiring to bed, with caution on subsequent up-titration.
Use with caution in patients prone to postural hypotension and in the elderly.
It may cause or worsen urinary incontinence, particularly in women.

Monitoring

Monitor lying and standing blood pressure, especially after the first dose and during dose increases.

Counselling the patient

Take the first dose at bedtime as it may make you dizzy or faint.
Stand up slowly, particularly when starting or increasing the dose.
Be cautious with activities such as driving until you know how it affects you.

Evidence & guidelines

Prazosin is a long-established selective alpha-1 blocker with a recognised first-dose hypotensive effect.

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

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways