Alpha Receptor Blockers
Examples
Doxazosin
Indications
- Hypertension (used in addition to other anti-hypertensives in refractory cases)
- Benign prostatic hyperplasia (BPH)
Contraindications
Caution:
- Micturation syncope
- Heart failure (may worsen symptoms)
- Hepatic impairment
Mechanism
Alpha blockers are selective antagonists of the vascular α1 adrenoreceptors, causing a fall in total peripheral resistance.
Non-selective α1 blockers are available for specialist use in phaeochromocytoma.
Administration
Oral
Adverse Reactions
- Postural hypotension, particularly first dose
- Gastro-intestinal disturbances (including nausea, vomiting, diarrhoea, constipation)
- Oedema
- Impotence
- Urinary incontinence (especially in women)
Interactions
The hypotensive effects of diuretics, blockers, calcium channel antagonists and antidepressants are potentiated by alpha blockers. This may be used for therapeutic effect.
Education
No specific issues
Pharmacokinetics
No specific issues
