Sympathomimetic Vasopressor (Alpha-Agonist)
Pregnancy: Use with caution — less studied in obstetrics than ephedrine or phenylephrine
Metaraminol
Brand names: Aramine
Adult dose
Dose: Bolus: 0.5–2 mg IV; Infusion: 15–100 mg in 500 mL sodium chloride 0.9%, titrated
Route: IV
Frequency: Bolus as needed; or continuous infusion
Max: Titrated to MAP target
Predominantly alpha-1 agonist — raises BP primarily by vasoconstriction. Some beta-1 activity — mild positive inotrope. Used for anaesthesia-induced hypotension and in ICU as a vasopressor bridge. More commonly used in UK than phenylephrine for general anaesthesia hypotension.
Paediatric dose
Dose: 0.01 mg/kg
Route: IV
Frequency: Bolus
Max: Titrated to response
Seek specialist opinion — used in paediatric anaesthesia for refractory hypotension.
Dose adjustments
Renal
No specific adjustment required.
Hepatic
No specific adjustment required.
Paediatric weight-based calculator
Seek specialist opinion — used in paediatric anaesthesia for refractory hypotension.
Clinical pearls
- Tissue necrosis on extravasation — use large-bore cannula in antecubital fossa; central line preferred for infusions
- Frequently used as a vasopressor bolus during general anaesthesia hypotension in UK anaesthetic practice
- For sustained vasopressor need in ICU: transition to noradrenaline via central line
Contraindications
- Hypertension
- MAOIs within 14 days
- Hypovolaemia (treat volume first)
Side effects
- Hypertension (if overdosed)
- Reflex bradycardia
- Tissue necrosis if extravasation (peripheral IV)
- Arrhythmias
Interactions
- MAOIs (hypertensive crisis)
- Beta-blockers (exaggerated hypertension via unopposed alpha)
- Ergometrine (additive vasoconstriction — avoid combined use in obstetrics)
Monitoring
- BP after each bolus
- IV site for signs of extravasation
- HR (reflex bradycardia)
Reference: BNFc; BNF 90; AAGBI Guidelines; RCoA Regional Anaesthesia Guidelines. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.