dopamine
catecholamine vasopressor· Brands: Intropin, DopastatIV
Mechanism of action
Dopamine is a naturally occurring catecholamine that acts as an agonist at alpha and beta adrenergic receptors and at dopamine receptors. Its effects are dose-dependent. At low doses (0.5-3 mcg/kg/min), it activates D1 and D2 dopamine receptors in renal, mesenteric, and coronary vasculature, causing vasodilation and increased renal blood flow. At moderate doses (3-10 mcg/kg/min), it stimulates beta-1 adrenergic receptors in the heart, increasing heart rate and contractility. At high doses (>10 mcg/kg/min), it activates alpha-1 adrenergic receptors, causing vasoconstriction and increased systemic vascular resistance.
Pharmacokinetics
Dopamine is given intravenously as it is not absorbed orally. Onset of action is rapid, within minutes. It is extensively metabolised in liver and other tissues by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) to inactive metabolites, mainly homovanillic acid. The plasma half-life is approximately 1-2 minutes, so continuous infusion is required. It is widely distributed but does not cross the blood-brain barrier significantly. Metabolites are excreted in urine.
Indications & dosing
Hypotension / shock (adult)
Titrate to blood pressure and organ perfusion; doses >10 mcg/kg/min cause vasoconstriction.
- adult · IV: 2–20 mcg/kg/min continuous · Titrate to blood pressure and organ perfusion; doses >10 mcg/kg/min cause vasoconstriction.
Symptomatic bradycardia
Used if atropine ineffective; administer via secure IV line with close monitoring.
- adult · IV: 2–10 mcg/kg/min continuous · Used if atropine ineffective; administer via secure IV line with close monitoring.
Shock (paediatric)
Titrate to clinical response; use a syringe pump for accurate dosing.
- pediatric · IV: 2–20 mcg/kg/min continuous · Titrate to clinical response; use a syringe pump for accurate dosing.
Shock (neonatal)
Use lower starting dose; monitor closely for blood pressure and heart rate.
- neonatal · IV: 2–20 mcg/kg/min continuous · Use lower starting dose; monitor closely for blood pressure and heart rate.
Contraindications & precautions
- Phaeochromocytoma · May precipitate hypertensive crisis.
- Tachyarrhythmias or ventricular fibrillation · Dopamine can exacerbate arrhythmias.
- Uncorrected hypovolaemia · Vasopressors may worsen tissue perfusion if volume is not restored.
- Use of monoamine oxidase inhibitors (MAOIs) · Risk of severe hypertension due to accumulation of catecholamines.
- Ensure adequate fluid resuscitation before use.
- Administer through a large vein, preferably a central line, to minimise risk of extravasation.
- Monitor blood pressure, heart rate, and ECG continuously during infusion.
- Use the lowest effective dose and titrate carefully.
- Correct hypovolaemia, acidosis, and electrolyte disturbances before starting dopamine.
- Wean the infusion gradually to avoid rebound hypotension.
Adverse effects
- Tachycardia
- Hypertension
- Nausea and vomiting
- Arrhythmiasserious
- Myocardial ischaemia or anginaserious
- Gangrene due to extravasationserious
- Headache
Monitoring, pregnancy & toxicity
- Blood pressure · frequently during infusion
- Heart rate and rhythm (ECG) · continuous ECG monitoring during infusion
- Urine output · hourly
- Peripheral perfusion and extravasation at infusion site · frequently, especially during dose titration
- Serum lactate · as clinically indicated
- Pregnancy: Dopamine is used in pregnancy only when the benefit outweighs the potential risk, as it may reduce uterine blood flow and cause fetal hypoxia. Use the lowest effective dose and monitor fetal heart rate if practicable.
- Toxicity: Excessive vasoconstriction causing hypertension and reduced tissue perfusion · Stop the infusion and treat hypertension with short-acting alpha-blockers if needed.
- Toxicity: Tachyarrhythmias (e.g., ventricular ectopy, tachycardia) · Stop the infusion and treat arrhythmias according to standard protocols.
- Toxicity: Extravasation causing tissue necrosis and sloughing · Stop the infusion, aspirate any residual drug, and infiltrate the affected area with phentolamine.
Antidotes & reversal
- Phentolamine (local infiltration) · Extravasation: stop infusion, aspirate, infiltrate phentolamine 5-10 mg in 10 mL saline locally.
Clinical notes
Dopamine is used in the management of hypotension, shock, and low cardiac output states. It is no longer a first-line vasopressor in many guidelines; norepinephrine is preferred in septic shock. Dose is titrated to haemodynamic response. It should be used with caution in patients with cardiac arrhythmias or ischaemic heart disease. Extravasation can cause tissue necrosis; treat with phentolamine. Avoid in patients with pheochromocytoma. Renal dose effects are not proven to improve outcomes.
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BNF; local formulary