Dopamine is one of the most important emergency cardiovascular drugs, frequently used in shock, acute heart failure, and ICU settings. It is also a classic exam favorite because of its dose-dependent receptor actions, which make it unique among catecholamines.
What Is Dopamine?
Dopamine is an endogenous catecholamine that acts as:
1. A neurotransmitter in the brainQuick Drug Profile
| Feature | Details |
|---|---|
| Drug class | Catecholamine |
| Route | Intravenous infusion |
| Nature | Endogenous |
| Key property | Dose-dependent effects |
| Main use | Shock, low cardiac output states |
Why Dopamine Is Special
Unlike most drugs, dopamine’s effect changes with dose.
This makes it extremely important for MCQs and clinical decision-making.
👉 Low dose = renal effects
👉 Moderate dose = cardiac effects
👉 High dose = vasopressor effects
Dopamine Receptors (Concept Review)
Dopamine acts on multiple receptors:
1. D₁ receptors – Renal & mesenteric vasodilationDose-Dependent Effects of Dopamine (Very High-Yield)
1. Low Dose Dopamine (1–3 µg/kg/min)
Receptor activated: D₁
Effects:
- Renal vasodilation
- ↑ Renal blood flow
- ↑ GFR
- ↑ Sodium excretion
Historically called “renal dose dopamine”
Now rarely recommended due to lack of survival benefit
2. Moderate Dose Dopamine (3–10 µg/kg/min)
Receptor activated: β₁
Effects:
- ↑ Heart rate
- ↑ Cardiac contractility
- ↑ Cardiac output
Useful in cardiogenic shock with hypotension
3. High Dose Dopamine (>10 µg/kg/min)
Receptor activated: α₁
Effects:
- Peripheral vasoconstriction
- ↑ Systemic vascular resistance
- ↑ Blood pressure
Acts as a vasopressor
One-Glance Dose Table (Exam Gold)
| Dose | Receptor | Main Effect |
|---|---|---|
| Low | D₁ | Renal vasodilation |
| Moderate | β₁ | Inotropy + chronotropy |
| High | α₁ | Vasoconstriction |
Mechanism of Action (Simplified)
Dopamine binds to dopamine, beta, and alpha receptors depending on dose.
One-Line Exam Answer
Dopamine shows dose-dependent receptor activation causing renal, cardiac, and vasopressor effects
Clinical Uses of Dopamine
1. Shock (Important)
- Cardiogenic shock
- Septic shock (selected cases)
- Hypotensive states with low cardiac output
Especially when bradycardia + hypotension coexist.
2. Acute Heart Failure
- Low cardiac output states
- Short-term hemodynamic support
3. ICU & Emergency Use
- Requires continuous BP and ECG monitoring
- Given only as IV infusion
When Dopamine Is Preferred
- Hypotension with bradycardia
- Patients needing inotropy + vasopressor support
- Temporary stabilization in emergency settings
Pharmacokinetics (Simplified)
| Parameter | Details |
|---|---|
| Route | IV infusion |
| Onset | Immediate |
| Half-life | ~2 minutes |
| Metabolism | MAO & COMT |
| Oral use | Ineffective |
Adverse Effects (High-Yield)
Cardiovascular
- Tachycardia
- Arrhythmias
- Hypertension (high dose)
Peripheral
- Vasoconstriction
- Extravasation → tissue necrosis
Phentolamine is used for extravasation injury.
Contraindications & Cautions
Use cautiously in:
- Pheochromocytoma
- Ventricular arrhythmias
- Hyperthyroidism
Dopamine vs Dobutamine (Common Exam Comparison)
| Feature | Dopamine | Dobutamine |
|---|---|---|
| Dose-dependent | Yes | No |
| Renal effect | Yes (low dose) | No |
| Vasoconstriction | High dose | Minimal |
| Bradycardia use | Useful | Less useful |
Dopamine is more versatile, but more arrhythmogenic.
Dopamine vs Norepinephrine
| Feature | Dopamine | Norepinephrine |
|---|---|---|
| Receptor profile | D₁, β₁, α₁ | α₁ > β₁ |
| Arrhythmias | More | Less |
| Septic shock | Alternative | First choice |
Important Exam-Oriented Points
- Works only by IV route
- Very short half-life
- Requires infusion pump
- No proven renal protection benefit
- Causes arrhythmias at high doses
Easy Memory Tricks
Dose Effects
“D → B → A”
(D₁ → β₁ → α₁ as dose increases)
Renal Dose
“Low dose = Kidney dose (but outdated)”
FAQs
1. What is dopamine mainly used for?
Dopamine is used in shock and acute low-output states.
2. Why is dopamine dose-dependent?
Different receptors are activated at different doses.
3. What is low-dose dopamine used for?
Historically for renal perfusion, but not recommended routinely now.
4. Which receptor causes dopamine’s cardiac effect?
β₁ receptors.
5. What happens at high doses of dopamine?
α₁-mediated vasoconstriction increases blood pressure.
6. Is dopamine an inotrope or vasopressor?
It can act as both, depending on dose.
7. What is the major adverse effect of dopamine?
Cardiac arrhythmias.
8. Can dopamine be given orally?
No, it is ineffective orally.
9. Which drug treats dopamine extravasation?
Phentolamine.
10. Is dopamine first-line in septic shock?
No, norepinephrine is preferred.
