Drug Dosing for Adrenaline, Atropine, and Pralidoxime
Adrenaline (Epinephrine)
For anaphylaxis and allergic emergencies, administer 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution) intramuscularly in adults and children ≥30 kg, or 0.01 mg/kg (maximum 0.3 mg) in children <30 kg, repeated every 5-10 minutes as needed 1.
Administration Details:
- Route: Intramuscular into anterolateral thigh (through clothing if necessary)
- Needle length: At least 1/2 to 5/8 inch to ensure intramuscular delivery
- Repeat dosing: Every 5-10 minutes based on clinical response
- Monitoring: Assess reaction severity and cardiac effects continuously
- Avoid repeated injections at the same site due to vasoconstriction-induced tissue necrosis risk 1
Cardiac Arrest Context:
For neonatal resuscitation, the intravenous/intraosseous dose is 0.01-0.03 mg/kg, repeated every 3-5 minutes during chest compressions 2. The endotracheal route requires 2-2.5 times the IV dose 3.
Atropine
For organophosphate or carbamate poisoning with severe symptoms (bronchospasm, bronchorrhea, seizures, significant bradycardia), give 2-4 mg IV initially in adults, doubling the dose every 5 minutes until full atropinization is achieved 4, 5.
Atropinization Targets:
- Clear chest on auscultation
- Heart rate >80/min
- Systolic blood pressure >80 mm Hg
- Cessation of secretions 5
Maintenance and Monitoring:
- Continue atropinization for at least 48 hours until cholinesterase activity reverses 5
- Consider atropine infusion for maintenance 4
- Critical caveat: Do NOT give atropine in the presence of significant hypoxia due to ventricular fibrillation risk 5
- Watch for atropine toxicity signs: delirium, hyperthermia, muscle twitching 5
Pediatric Dosing:
- Usual initial dose: 0.01-0.03 mg/kg 6
- For nerve agent poisoning in children >1 year: full Mark 1 kit dose (2 mg atropine) when weight-based dosing is impossible 7
Coronary Artery Disease:
Limit total dose to 0.03-0.04 mg/kg 6
Pralidoxime
For organophosphate poisoning, administer 1000-2000 mg IV as an infusion over 15-30 minutes initially in adults, with a second dose after 1 hour if muscle weakness persists, then every 10-12 hours as needed 5.
Administration Guidelines:
- Preferred method: IV infusion in 100 mL normal saline over 15-30 minutes
- Alternative: Slow IV push over ≥5 minutes as 50 mg/mL solution (if pulmonary edema present)
- Maximum infusion rate: 200 mg/minute to avoid temporary worsening of cholinergic symptoms (tachycardia, cardiac arrest, laryngospasm, muscle rigidity) 5
- If IV not feasible: intramuscular or subcutaneous injection 5
Timing and Duration:
- Most effective when given early (before acetylcholinesterase "aging" occurs) 4
- Little benefit if given >36 hours after exposure termination 5
- Continue dosing as long as poisoning signs recur, particularly with ingested organophosphates due to continued GI absorption 5
- Observe patients for 48-72 hours minimum 5
Evidence Quality:
The 2023 AHA guidelines give pralidoxime a Class 2a recommendation (reasonable to use) for organophosphate poisoning 4. Animal studies suggest 40 mg/kg is optimal during cardiac arrest, while 120 mg/kg may worsen outcomes 8. Recent clinical data support combining pralidoxime with atropine and hemoperfusion for improved outcomes 9.
Important Caveats:
- Pralidoxime does NOT reverse carbamate-induced cholinesterase inhibition effectively, but should not be withheld when poison class is unknown 4
- Always give atropine first after correcting hypoxemia 5
- Avoid succinylcholine and mivacurium (cholinesterase-metabolized neuromuscular blockers) in organophosphate/carbamate poisoning 4