Second-lineCardura / Hypovase
Doxazosin / Prazosin
Selective α1-adrenergic antagonist
Add-on for multi-drug resistant hypertension in pregnancy.
Oral
First-line for
- Resistant HTN in pregnancy (add-on)
- HTN with phaeochromocytoma (prazosin, pre-op)
Mechanism
Selective α1 blockade → arteriolar + venous dilation without reflex tachycardia via central β sparing.
"First-dose syncope"
- Start at bedtime
- Titrate slowly
- Add-on, not first-line
- Useful in phaeochromocytoma
Dosing
- Doxazosin start
- 1 mg OD at bedtime
- Doxazosin titrate
- Double q1–2 weeks to max 16 mg/day
- Prazosin
- 500 μg TDS, titrate to 20 mg/day
Contraindications
- AbsoluteHistory of orthostatic hypotension / syncope
- CautionConcurrent PDE5 inhibitors, diuretics
Side effects
- First-dose syncope
- Postural hypotension
- Nasal congestion
- Fatigue
- Peripheral oedema
Fetal & maternal notes
- • Limited human data but no signal for teratogenicity
- • Preferred α-blocker for phaeochromocytoma in pregnancy
Key interactions
Sildenafil / tadalafil
AvoidProfound hypotension
Diuretics
CautionEnhanced first-dose effect
Clinical pearls
- 💡 First dose ALWAYS at bedtime
- 💡 Add when labetalol + nifedipine fail to control BP
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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