ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Combined Alpha-1 and Beta-Adrenergic Blocker Pregnancy: Safe in pregnancy — first-line for acute severe hypertension in pre-eclampsia/eclampsia (NICE NG133); monitor neonate for bradycardia and hypoglycaemia

Labetalol (IV — Hypertensive Emergency)

Brand names: Trandate

Adult dose

Dose: Bolus: 50 mg IV over 1 minute, repeat every 5 minutes to max 200 mg; Infusion: 2 mg/min (diluted to 1 mg/mL), titrate to response; Eclampsia/severe hypertension in pregnancy: 20–50 mg IV bolus
Route: Intravenous bolus or infusion
Frequency: Repeated boluses every 5 minutes or continuous infusion
Max: 200 mg bolus total; infusion up to 300 mg over 24h
Hypertensive emergency — aortic dissection (Type A/B), hypertensive encephalopathy, eclampsia; provides smooth BP reduction without reflex tachycardia; preserve DBP ≥90 mmHg in aortic dissection; target SBP <140 mmHg in eclampsia

Paediatric dose

Dose: 0.2–1 mg/kg IV over 2 minutes; infusion 0.25–3 mg/kg/hour mg/kg
Route: Intravenous
Frequency: Titrated to response
Max: 3 mg/kg/hour infusion
Paediatric hypertensive emergency: specialist critical care use; monitor for bradycardia and bronchospasm

Dose adjustments

Renal

No dose adjustment required

Hepatic

Reduce dose in severe hepatic impairment — hepatic metabolism

Paediatric weight-based calculator

Paediatric hypertensive emergency: specialist critical care use; monitor for bradycardia and bronchospasm

Clinical pearls

  • Aortic dissection: labetalol is first-line — combined alpha+beta blockade lowers HR and BP simultaneously; target HR <60 bpm + SBP 100-120 mmHg to reduce aortic shear stress; beta-blockade given BEFORE vasodilators (pure vasodilators cause reflex tachycardia worsening dissection)
  • Eclampsia/pre-eclampsia: labetalol IV is NICE NG133 first-line for acute severe hypertension in pregnancy (SBP ≥160 or DBP ≥110) — safe in pregnancy, crosses placenta minimally; neonatal bradycardia/hypoglycaemia possible with prolonged use near delivery
  • Supine position mandatory during IV labetalol: alpha-1 blockade causes profound postural hypotension — patient must be flat; avoid upright position for 3 hours post-infusion; blood pressure measured supine
  • Alpha:beta selectivity ratio: IV labetalol has 1:3 alpha:beta ratio (alpha-1 + non-selective beta-1/2); oral labetalol 1:7 ratio; this selectivity profile provides antihypertensive effect without the excessive reflex tachycardia of pure vasodilators
  • Phaeochromocytoma: labetalol is NOT recommended for phaeochromocytoma — despite combined alpha/beta blockade, incomplete and poorly balanced blockade may worsen hypertension; use phenoxybenzamine (alpha-1) first, then add beta-blocker (alpha-first rule)

Contraindications

  • Uncompensated cardiac failure
  • Cardiogenic shock
  • Asthma/severe reactive airway disease (beta-blockade)
  • 2nd/3rd degree heart block
  • Severe bradycardia (<50 bpm)

Side effects

  • Postural hypotension (common — keep patient supine)
  • Bradycardia
  • Bronchospasm (beta-blockade — avoid in asthma)
  • Nausea
  • Scalp tingling (characteristic — benign, alpha-1 effect)
  • Hepatotoxicity (rare — oral form association)
  • Fatigue

Interactions

  • Other antihypertensives — additive hypotension
  • Cimetidine — increases labetalol bioavailability (oral)
  • Halothane — additive hypotension in anaesthesia

Monitoring

  • Blood pressure (every 1-2 minutes during bolus phase, then every 5 min during infusion)
  • Heart rate (target <70 bpm, avoid <50 bpm)
  • SpO2 (bronchospasm)
  • Fetal heart rate monitoring (in obstetric context)
  • Urine output

Reference: BNFc; BNF 90; NICE NG133 (Hypertension in Pregnancy); ESC Aortic Diseases Guidelines 2014; MHRA SPC Trandate; AHA/ACC Hypertensive Crisis Guidelines 2017. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators