Adrenaline (Treatment)
1. Overview
Adrenaline is an endogenous catecholamine, and is used pharmacologically as a sympathomimetic agent. It acts on the ฮฒ and ฮฑ adrenoreceptors with dose-dependent selectivity. It is used to treat anaphylaxis, symptomatic bradycardia (e.g. in ฮฒ-blocker toxicity), and cardiac arrest.
2. Toxicologic Indications & Dosing
2.1 Anaphylaxis
- Also see: anaphylaxis.
- Adult:
- ๐ Adrenaline 0.5 mg IM (0.5 mL of 1:1,000), q5min PRN.
- Child:
- ๐๐ถ Adrenaline 10 micrograms/kg IM (0.01 mL/kg of 1:1,000), q5min PRN. Min dose 0.1 mL, max dose 0.5 mL.
- IV adrenaline may be given only by experienced specialists in an appropriate setting, as the dose requirements are different.
2.2 Bradycardia
- Also see: Beta Blocker Toxicity.
- Adult:
- ๐ Adrenaline 5-20 microgram IV, q3min PRN.
- ๐ Adrenaline 2-10 microgram/min IV infusion, titrate to response.
- Child:
- ๐๐ถ Adrenaline 10 microgram/kg IV (0.1 mL/kg of 1:10,000), q3min PRN.
- ๐๐ถ Adrenaline 0.1-1.5 microgram/kg/min IV infusion, titrate to response.
2.3 Cardiac Arrest
- Also see: cardiac arrest.
- Adult: ๐ Adrenaline 1 mg IV, every 2 cycles.
- Child: ๐๐ถ Adrenaline 10 microgram/kg IV, every 2 cycles.
3. Cautions & Contraindications
There are no absolute contraindications to the use of adrenaline in a life-threatening situation.
- Overtreatment may result in hypertension and tachyarrhythmias.
- โ serum lactate.
- Myocardial ischemia.
4. Special Populations
Pregnancy rating: A (AU/NZ)
Lactation: Excreted in breast milk, but potential effects on breastfed infant is unknown.
5. Adverse Effects
- CVS: hypertension, tachyarrhythmias, myocardial ischemia.
- CNS: anxiety, tremor.
- Skin: tissue necrosis if extravasates.
- Metabolic: hyperglycemia, hyperlactatemia.
6. Pharmacology
6.1 Pharmacodynamics
Mechanism of action: Dose-dependent adrenoceptor activity, with ฮฒ-agonist effects predominate at low doses, and added ฮฑ-agonist effects at higher doses.
6.2 Pharmacokinetics
Absorption:
- Oral bioavailability: 0%.
Distribution:
- Vd: 0.1-0.2 L/kg.
- Lipid solubility:
- Does not cross BBB
- Crosses placenta
- Excreted in breast milk
- Protein binding: 50%
Metabolism: Rapidly metabolized by COMT and MAO into metanephrine and 3,4-dihydroxymandelic acid, then ultimately into vanillylmandelic acid.
Excretion:
- Elimination tยฝ: 2-3 mins.
- Renal clearance: Renally excreted, mostly as inactive metabolites.
6.3 Pharmaceutics
Formulation:
- Ampoules containing 1000 microgram/1 mL or 1000 microgram/10 mL.
- Autoinjector with varying doses (commonly 0.15 mg, 0.3 mg, 0.5 mg). Various brands exist, e.g. EpiPen, Emerade, Auvi-Q.
7. References
Useful general references: