What is the sequence of administration for adrenaline (epinephrine), chlorpheniramine maleate, ranitidine, and hydrocortisone in the management of anaphylaxis?

Sequence of Drug Administration in Anaphylaxis Management

In anaphylaxis, epinephrine (adrenaline) must be administered FIRST, followed by chlorpheniramine maleate, ranitidine, and hydrocortisone as adjunctive therapies. 1, 2

Correct Sequence of Administration:

1. Epinephrine (First-line treatment)

   • Must be administered immediately as the first medication 2
   • Intramuscular injection into the anterolateral thigh is the preferred route 2, 3
   • Adult dose: 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution) 1, 2
   • May need to be repeated every 5-15 minutes if symptoms persist 1, 2

2. Chlorpheniramine maleate (H1 antihistamine)

   • Administer only after epinephrine 1, 2
   • Adult dose: 10 mg IV 1
   • Should never be used alone to treat anaphylaxis 1, 2

3. Ranitidine (H2 antihistamine)

   • Administer after H1 antihistamine 1
   • Adult dose: 50 mg IV (diluted in 5% dextrose to 20 mL, injected over 5 minutes) 1
   • Combination of H1 and H2 antihistamines is superior to H1 antihistamine alone 1, 2

4. Hydrocortisone (Corticosteroid)

   • Administer last in the sequence 1
   • Adult dose: 200 mg IV 1
   • Not helpful for acute management but may prevent biphasic or protracted reactions 1, 2

Important Clinical Considerations:

• Epinephrine is the ONLY life-saving medication in anaphylaxis management and should never be delayed 2, 3, 4
• Antihistamines and corticosteroids are adjunctive treatments and should never replace or delay epinephrine administration 1, 2, 5
• Delay in administering epinephrine has been associated with anaphylaxis fatalities 2, 4
• For severe cases with hypotension refractory to initial management, consider epinephrine infusion 1

Common Pitfalls to Avoid:

• Delaying epinephrine administration while giving antihistamines first 2, 5
• Using subcutaneous instead of intramuscular injection for epinephrine (delays absorption) 2, 4
• Administering intravenous epinephrine outside of monitored settings (reserved for cardiac arrest or profound hypotension unresponsive to IM epinephrine) 2
• Relying solely on antihistamines or corticosteroids for treatment 1, 2, 5

Post-Treatment Monitoring:

• All patients should be observed for 4-6 hours or longer based on reaction severity 1, 5
• Monitor for biphasic reactions (recurrence without re-exposure) 1, 5
• Consider transfer to an emergency department or intensive care facility 1

Remember that these medications are administered in this specific sequence because epinephrine addresses the life-threatening aspects of anaphylaxis immediately, while the other medications provide supplementary relief and help prevent symptom recurrence.