What is the recommended dose and administration of epinephrine (adrenaline) for an adult patient with a history of chronic migraines presenting with anaphylaxis or a severe allergic reaction?

Epinephrine 0.3mg Treatment Guide for Anaphylaxis

For an adult patient with anaphylaxis, administer 0.3-0.5 mg of epinephrine (1:1000 concentration) intramuscularly into the anterolateral thigh immediately, and repeat every 5 minutes as needed until symptoms resolve. 1, 2

Initial Dosing and Administration

Standard adult dose is 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution) administered intramuscularly into the mid-outer thigh (vastus lateralis muscle) at a 90-degree angle. 1, 3, 2

• The intramuscular route in the lateral thigh achieves peak plasma concentrations in 8±2 minutes, compared to 34±14 minutes with subcutaneous deltoid injection 3, 4
• Injection can be given through clothing if necessary during emergency situations, as delay in administration is associated with increased mortality 3
• The history of chronic migraines is irrelevant to epinephrine dosing—there are no absolute contraindications to epinephrine in anaphylaxis 2, 5

Repeat Dosing Protocol

Repeat the same dose (0.3-0.5 mg IM) every 5 minutes if symptoms persist, worsen, or recur. 2, 3

• Approximately 10-20% of patients require more than one dose before symptom recovery 2
• The 5-minute interval can be liberalized to permit more frequent injections if clinically deemed necessary 4, 3
• There is no maximum number of IM epinephrine doses—continue every 5 minutes as needed until symptoms resolve 2
• Most patients require 1-2 doses, but some need more 2

Critical Pitfalls to Avoid

Delaying epinephrine administration is the primary cause of anaphylaxis fatalities—not giving multiple doses. 2, 3

• Do not delay epinephrine while giving antihistamines or corticosteroids first 3
• Do not stop at one dose prematurely if symptoms persist or progress 2
• Do not confuse concentrations: always use 1:1000 (1 mg/mL) for IM injection; 1:10,000 is reserved for IV use only 2
• Do not inject into the deltoid, buttocks, digits, hands, or feet 1, 3

Concurrent Management

While administering epinephrine, simultaneously:

• Call 911 or activate the resuscitation team immediately 2
• Position the patient supine with legs elevated—never allow standing or walking, as this increases mortality risk 2
• Prepare for IV fluid resuscitation with normal saline bolus of 1000-2000 mL for refractory hypotension 2

When to Escalate to IV Epinephrine Infusion

If the patient fails to respond to multiple IM doses (typically 2-3 doses) and remains profoundly hypotensive despite IV fluid resuscitation, transition to IV epinephrine infusion. 6, 2

IV Epinephrine Preparation and Dosing:

• Add 1 mg (1 mL) of 1:1000 epinephrine to 250 mL of D5W to yield a concentration of 4.0 mcg/mL 6, 4
• Start infusion at 1-4 mcg/min (15-60 drops/min with microdrop apparatus) 6, 2
• Titrate up to a maximum of 10 mcg/min based on clinical response and side effects 6, 4
• Continuous hemodynamic monitoring is essential—if unavailable, perform every-minute blood pressure measurements, continuous pulse monitoring, and ECG monitoring 6, 4

Alternative IV Preparation Method:

• Add 1 mg (1 mL) of 1:1000 epinephrine to 100 mL of saline to create a 1:100,000 solution 6, 4
• Infuse at 30-100 mL/hr (5-15 mcg/min), titrated based on clinical response 6, 4

Adjunctive Therapies (Second-Line Only)

After epinephrine administration, consider:

• H1 antihistamine: Diphenhydramine 25-50 mg parenterally 4
• H2 antihistamine: Ranitidine 50 mg IV over 5 minutes (combination with H1 is superior to H1 alone, but both are second-line to epinephrine) 4
• Corticosteroids: Hydrocortisone or equivalent for patients with history of asthma or severe/prolonged anaphylaxis (not helpful acutely but may prevent biphasic reactions) 4, 2
• Inhaled beta-agonist: Nebulized albuterol 2.5-5 mg for bronchospasm resistant to epinephrine 4

Special Considerations for This Patient

The chronic migraine history does not alter epinephrine dosing or contraindicate its use 2, 5. The risk of death from untreated anaphylaxis far exceeds any risk of epinephrine-related adverse effects, even in patients with comorbidities 2.

Post-Treatment

• Transport to emergency department via EMS for observation, even if symptoms resolve, as biphasic reactions can occur up to 72 hours later (mean 11 hours) 3, 2
• Prescribe two epinephrine autoinjectors (0.3 mg) for home use with proper instruction 2, 4
• Refer to allergist-immunologist for follow-up 4