title: "Adrenaline (Epinephrine)"
Adrenaline (Epinephrine)
Adrenaline is the first-line drug for anaphylaxis and a key medication in cardiac arrest. Know the doses and routes.
Mechanism of Action
Adrenaline is an endogenous catecholamine with both α and β adrenergic effects:
| Receptor | Effect | Clinical Application |
|---|---|---|
| α₁ | Vasoconstriction | ↑ SVR, ↑ BP, ↓ mucosal oedema |
| β₁ | ↑ HR, ↑ contractility | ↑ Cardiac output |
| β₂ | Bronchodilation, vasodilation | Relieves bronchospasm |
Indications
1. Anaphylaxis (First-Line)
Anaphylaxis dose: 0.5 mg IM (500 mcg) into lateral thigh. This is 0.5 mL of 1:1000 adrenaline.
Source: ASCIA Guidelines.
- Give IM, not SC (faster absorption)
- Repeat every 5 minutes if no improvement
- Children: 0.01 mg/kg (max 0.5 mg)
Never give 1:1000 IV. IV adrenaline (outside of cardiac arrest) should be diluted and titrated/infused by an experienced clinician; 1:10,000 (0.1 mg/mL) is the standard arrest preparation.
Source: ASCIA Guidelines; ANZCOR.
2. Cardiac Arrest
Cardiac arrest dose: 1 mg IV (10 mL of 1:10,000) every 3-5 minutes.
Source: ANZCOR Guideline 11.5.
- Given in all cardiac arrest rhythms
- Shockable: give after 2nd shock, then every 2 cycles
- Non-shockable: give immediately, then every 2 cycles
- Mechanism: improves coronary and cerebral perfusion pressure
3. Vasopressor Support
- Infusion: 0.01-0.5 mcg/kg/min
- Used when noradrenaline insufficient
- Provides both α and β effects
- Useful in anaphylactic shock, bradycardia with hypotension
4. Upper Airway Obstruction (e.g., Croup/Stridor)
- Nebulised adrenaline: 5 mg (5 mL of 1:1000) for severe upper airway obstruction/stridor (per local protocols)
- Not routine therapy for lower airway asthma unless anaphylaxis is suspected
Preparations
| Preparation | Concentration | Volume | Common Use |
|---|---|---|---|
| 1:1000 | 1 mg/mL | 1 mL ampoule | IM for anaphylaxis |
| 1:10,000 | 0.1 mg/mL | 10 mL syringe | IV for cardiac arrest |
| Infusion | Variable | 50 mL syringe | ICU vasopressor |
1:1000 = 1 mg/mL (one thousand = one mg) 1:10,000 = 0.1 mg/mL (ten thousand = tenth of a mg)
Adverse Effects
- Tachyarrhythmias (VT, VF in overdose)
- Hypertension
- Tremor, anxiety
- Tissue necrosis if extravasation (with infusion)
Clinical Pearls
In anaphylaxis, the lateral thigh is preferred over deltoid - larger muscle mass, better absorption, easier self-administration.
If patient on beta-blockers, anaphylaxis may be refractory to adrenaline. Consider glucagon 1-2 mg IV.
Source: ASCIA Guidelines.
Test Your Knowledge
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