Epinephrine (EPI)

Names

Generic

Epinephrine

Brand

EpiPen, Auvi-Q, Adrenaclick, Adrenalin

Indications and Dosing

Epinephrine is available in two different concentrations:

1 mg/mL for intramuscular (IM) administration
0.1 mg/mL for intravenous (IV) administration

When given as an IV infusion (IV drip) the 1 mg / mL concentration should be diluted.
Dilution will be dependent upon patient condition and hospital policies.

Cardiac Arrest

Cardiac Arrest Benefit:

Cardiac myocyte excitation causing increases in:
heart rate
contractility
coronary perfusion pressure

Route:

Intravenous (IV) or Intraosseous (IO)

In cardiac arrest Epi is always given via IV or IO access.

Endotracheal Tube (ETT) Administration

In emergency situations where IV or IO access is non-existent, Epi may be administered through an ETT to be absorbed through the alveoli.

IV or IO access should ALWAYS be the priority due to lack of data regarding medication administration through ETT.

Dosing:

Pediatric Weight Based Formula:
sssssssssssssPediatric IV: 0.01 mg/kg of the 0.1mg/mL solution
sssssssssssssPediatric ETT: 0.01 mg/kg of the 0.1mg/mL solution

Common Dosages:
sssssssssssssPediatrics: 0.01 mg/kg every 3 to 5 minutes
sssssssssssssAdults: 1mg every 3 to 5 minutes

Anaphylaxis

Anaphylaxis Benefit:

Bronchodilation leading to improved ventilation

Route:

Intramuscular (IM)
Injection to be given in a large muscle with a considerable amount of blood flow.
This is most often given in the side of the thigh muscle (vastus lateralis).
This injection may be given through clothes due to the emergent nature of administering it.

Intravenous (IV)
In certain circumstances Epi may be given IV for anaphylaxis.
Consult your hospital policies for instructions and dosing.

Dosing:

Pediatric Weight Based Formula:
sssssssssssssPediatric IM: 0.01 mg/kg of the 1mg/mL concentration
sssssssssssssPediatric IV: 0.01 mg/kg of the 0.1mg/mL concentration

Adult Dosage Ranges:
sssssssssssssAdult IM: 0.2 – 0.5 mg of the 1mg/mL concentration
sssssssssssssAdult IV: 0.1–0.25 mg of the 0.1mg/mL concentration

Common Dosages:
sssssssssssss0.3 mg for patients weighing ≥30 kg
sssssssssssss0.15 mg for patients weighing 15–30 kg

Other Indications

Pupil dilation (mydriasis) during intraocular surgeries

Hypotension during septic and anaphylactic shock

Croup via nebulization

Severe asthma exacerbation’s via nebulization

Local anesthetic block

Contraindications

Precaution: Geriatric

Precaution: Pediatrics

Precaution: Pregnancy

Precaution: Labor and Delivery

Shock unless shock is caused by anaphylaxis or sepsis

Hypersensitivity

Class: Adrenergic

These medications are considered to be “sympathomimetic”, meaning they mimic functions of the sympathetic nervous system.

Adrenergic medications bind to adrenergic receptors throughout the body.
These receptors include: alpha-1, alpha-2, beta-1, beta-2, and beta-3 receptors.

Each receptor controls different bodily functions, which are:

Alpha-1: Smooth muscle contraction, mydriasis
Alpha-2: Mixed smooth muscle effects
Beta-1: Increased cardiac chronotropic and inotropic effects
Beta-2: Bronchodilation
Beta-3: Increased lipolysis

Pharmacodynamics

Pharmacodynamics is the study of what a drug does to the body.
Here Mechanism of Action and Toxicity will be covered.

Mechanism of Action

Acts upon adrenergic receptors throughout the body including alpha-1, alpha-2, beta-1, beta-2, and beta-3 receptors.

Effects include:
Increased heart rate
Increased myocardial contractility
Vasoconstriction
Bronchodilation
Smooth muscle contraction
Increased renin production
Tocolysis
Increased aqueous humor production

Toxicity

Vesicant
ssssss Extravasation protocols should be used in the event of IV infiltration.

Drug induced liver injury
ssssss May cause liver injury due to liver involvement in metabolism

Pharmacokinetics

Pharmacokinetics is the study of what the body does to the drug.
Here Absorption, Metabolism, Half-Life, and Excretion will be covered.

Absorption

IV:
ssss Rapid onset due to direct distribution into blood stream.

IM:
ssss Effects begin within 5 to 10 minutes

Metabolism

Mostly metabolized by the liver by a combination of reactions involving the enzymes catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO)

Half-Life

2 to 3 minutes once it enters the blood stream

Since IM injections take longer to enter the blood stream half-life will be increased due to the increased time of absorption.

Excretion

Excreted through urine after being metabolized

Adverse Effects

*Tachycardia
Depending upon the condition this is expected.
In anaphylaxis it is not uncommon for the patient to wind up tachy which is expected and should be monitored.

Hypertension

Dysrhythmias

Angina

Tremors

Anxiety

Medication Interactions

Alpha-adrenergic blockers (decreased pressor effect)

Antihypertensives (decreases pressor effect)

Vasodilators (decreases pressor effect)

Diuretics (decreases pressor effect)

Beta Blockers (increases pressor effect)

MAO inhibitors (increases pressor effect)

COMT inhibitors (increases pressor effect)

References

American Society of Health-System Pharmacists. (2022, March 2). Epinephrine monograph for professionals. Drugs.com. https://www.drugs.com/monograph/epinephrine.html

Dalal, R., & Grujic, D. (2023, May 1). Epinephrine. statpearls. Retrieved February 5, 2024 from https://www.ncbi.nlm.nih.gov/books/NBK482160/

National Center for Biotechnology Information (2024). PubChem Compound Summary for CID 5816, Epinephrine. Retrieved February 6, 2024 from https://pubchem.ncbi.nlm.nih.gov/compound/Epinephrine.

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