How to prepare and administer an intramuscular (IM) adrenaline (epinephrine) injection, such as an EpiPen (epinephrine auto-injector)?

Preparation and Administration of Intramuscular Adrenaline (Epinephrine)

For anaphylaxis treatment, inject adrenaline intramuscularly into the anterolateral thigh (vastus lateralis muscle) using 1:1000 concentration (1 mg/mL), with doses of 0.3-0.5 mg for adults and 0.01 mg/kg (maximum 0.3 mg) for children, repeated every 5-10 minutes as needed. 1

Preparation Steps

Verify Correct Concentration

• Always confirm you have 1:1000 (1 mg/mL) concentration for intramuscular injection - using the wrong concentration (1:10,000) can result in fatal underdosing 2
• Inspect the solution visually before administration - do not use if colored, cloudy, or contains particulate matter 1

Equipment Needed

• 1 mL syringe with a needle at least 1/2 to 5/8 inch (12.7-15.9 mm) long to ensure intramuscular delivery 1
• Adrenaline 1:1000 solution (1 mg/mL) 1

Drawing Up the Dose

• Adults and children ≥30 kg: Draw up 0.3-0.5 mL (0.3-0.5 mg), maximum 0.5 mg per injection 1
• Children <30 kg: Draw up 0.01 mL/kg (0.01 mg/kg), maximum 0.3 mL (0.3 mg) per injection 1

Administration Technique

Injection Site

• Inject into the anterolateral aspect of the mid-thigh (vastus lateralis muscle) - this is the only recommended site for first-aid treatment 3
• This site achieves peak plasma concentrations in 8±2 minutes, compared to 34±14 minutes with subcutaneous deltoid injection 3
• The injection can be given through clothing if necessary 1

Injection Procedure

• Hold the leg firmly in place when administering to children to minimize injection-related injury and limit movement 1
• Insert the needle at a 90-degree angle to ensure intramuscular delivery 3
• Inject the full dose rapidly 1
• Do not inject repeatedly at the same site - rotate injection sites as vasoconstriction may cause tissue necrosis 1

Repeat Dosing Protocol

When to Repeat

• Repeat injection every 5-10 minutes if symptoms fail to resolve or worsen 1
• Approximately 10-20% of patients require more than one dose 4
• There is no maximum number of doses - continue every 5 minutes as needed until symptoms resolve 4

Monitoring Between Doses

• Monitor clinically for severity of allergic reaction and potential cardiac effects 1
• Assess respiratory status, blood pressure, and level of consciousness 3

Critical Safety Points

Route Selection

• Never use subcutaneous route - intramuscular injection in the thigh is superior and provides more rapid, higher peak plasma levels 3
• Avoid intravenous administration in first-aid settings - IV route carries significant risk of dilution/dosing errors and serious adverse effects, and should be reserved for cardiac arrest or refractory shock in hospital settings with continuous monitoring 3

Contraindications

• There is no absolute contraindication to epinephrine in anaphylaxis - the risk of death from untreated anaphylaxis far exceeds any risk from epinephrine, even in elderly patients or those with cardiovascular disease 3, 4

Common Pitfalls to Avoid

• Delaying administration is associated with increased mortality - inject immediately upon recognition of anaphylaxis 2
• Confusing concentrations (1:1000 vs 1:10,000) can lead to fatal errors - always verify before drawing up 2
• Using the deltoid or subcutaneous route results in delayed absorption and suboptimal treatment 3
• Stopping after one dose when symptoms persist or progress - continue dosing every 5 minutes as clinically indicated 4
• Failing to call emergency services - always activate EMS even if symptoms improve, as biphasic reactions can occur 4

Post-Administration Management

• Position patient supine with legs elevated (unless respiratory distress prevents this) 4
• Never allow the patient to stand or walk - this increases mortality risk 4
• Transport to emergency department for observation even if symptoms resolve 4
• Consider supplemental oxygen, IV fluids, antihistamines, and corticosteroids as adjunctive therapy 3, 4