Cardiovascular/Alpha-blocker

Alpha-blockers

also: doxazosin · tamsulosin · alfuzosin · -osin

Overview

α₁-antagonists — step-4 add-on for resistant hypertension (if K⁺ >4.5) and first-line medical therapy for benign prostatic hyperplasia (BPH).

Mechanism

Selective α₁-adrenoceptor antagonism → vascular smooth-muscle relaxation (↓peripheral resistance, ↓BP) and relaxation of prostatic/bladder-neck smooth muscle (improved urinary flow in BPH).

Indications

Resistant hypertension (step 4 alternative)
Benign prostatic hyperplasia (LUTS)
Phaeochromocytoma — α-blockade BEFORE β-blockade

The agents

Doxazosinlong-acting (vascular)

Resistant HTN (NICE step 4 if K⁺ >4.5).

Tamsulosin / alfuzosinuroselective

BPH — more prostate-selective, less hypotension.

Adverse effects

First-dose / postural hypotensionclassic

Take the first dose at bedtime.

Dizziness, headachecommon

Intraoperative floppy iris syndromeserious

Tamsulosin — tell the ophthalmologist before cataract surgery.

Retrograde ejaculationcommon

Cautions & contraindications

Postural hypotension / history of fallselderly

Unopposed use in phaeochromocytoma is correct ORDER (α before β)all

Interactions

Additive hypotension with other antihypertensives, PDE-5 inhibitors

Monitoring & kinetics

Lying/standing BP,Urinary symptoms (BPH)

Oral. Warn re first-dose hypotension.

Source: BNF — Alpha-adrenoceptor blocking drugs · NICE NG136 — Hypertension