Anaes · Anaesthetic adjuncts

Noradrenaline

Also known as Norepinephrine · Direct-acting catecholamine vasopressor · Alpha-1 greater than beta-1 agonist · First-line septic shock vasopressor

Noradrenaline (norepinephrine) is the physiological NEUROTRANSMITTER of the sympathetic nervous system and a DIRECT-ACTING CATECHOLAMINE synthesised from dopamine by dopamine-beta-hydroxylase. Its receptor profile is potent ALPHA-1 vasoconstriction plus moderate BETA-1 inotropy and chronotropy plus presynaptic ALPHA-2 autoreceptor activity, with a NET ALPHA-DOMINANT effect (alpha greater than beta) and crucially NO beta-2 activity. The alpha-1 vasoconstriction raises systemic vascular resistance and blood pressure; the baroreceptor response to that pressure rise produces the characteristic REFLEX BRADYCARDIA. Cardiac output is MAINTAINED or slightly decreased because the beta-1 inotropy offsets the increased afterload, and cardiac output is better preserved than with a pure alpha-1 agent such as phenylephrine precisely because of this beta-1 component (taught comparison; no output-comparison primary in-file). Noradrenaline is the taught FIRST-LINE vasopressor for SEPTIC SHOCK and the Surviving Sepsis Campaign recommended first-line agent for vasodilatory shock (taught place-in-practice; no guideline primary in-file), and it is also used for neurogenic shock and perioperative vasoplegia (taught uses). Its very short half-life of about 2 to 3 minutes mandates a CONTINUOUS IV INFUSION at 0.05 to 1.0 micrograms per kg per min (taught kinetics and formulary; local protocol governs), it is metabolised by COMT and MAO (taught), and its principal adverse effects are peripheral and digital ischaemia from excessive alpha-1 vasoconstriction, arrhythmias (less than adrenaline because of the absent beta-2 effect), hypertension, reflex bradycardia, and reduced splanchnic and renal perfusion at high doses (taught risks), plus EXTRAVASATION tissue necrosis that is treated with phentolamine infiltration (peripheral-vasopressor cohort: 31 of 3734 peripherally initiated patients, 0.8%, received phentolamine — Shyu 2025). The absence of beta-2 activity distinguishes it from adrenaline: noradrenaline produces less tachycardia, no bronchodilation, and no metabolic hyperglycaemia, hypokalaemia or lactate rise (taught contrast). Built on the neonatal fluid-refractory septic shock first-line vasopressor systematic review (Yahya 2026, 4-RCT neonatal scope only), the vasopressor selection and postoperative delirium study in older adults (Dong 2026, delirium-null scope only), the peripheral vasopressor safety cohort (Shyu 2025, extravasation scope), and the physiological difficult airway management study (Ghaffar 2026, airway scope only).

Checked against its sources on 11 Sept 2026