Atropine Dosing for Organophosphate Poisoning
For organophosphate poisoning, the recommended initial dose of atropine is 2-3 mg intravenously, repeated every 20-30 minutes until muscarinic symptoms are controlled. 1
Dosing Protocol
- Initial dose: 2-3 mg IV for adults 1
- Frequency: Repeat every 20-30 minutes as needed based on clinical response 1
- Route: Intravenous administration is preferred for rapid effect 1
- Titration: Continue dosing until control of muscarinic symptoms (excessive secretions, bronchospasm, bradycardia) 2
- Total dose: May require very high cumulative doses (up to several grams) in severe cases 2
Clinical Indicators for Atropine Administration
- Presence of muscarinic symptoms: excessive secretions, bronchospasm, bradycardia, miosis 3
- Hemodynamic compromise: hypotension, altered mental status 4
- Respiratory distress: bronchorrhea, bronchospasm 2
- Goal of therapy: drying of secretions, normalization of heart rate, improved oxygenation 2
Special Considerations
- Severe cases may require continuous IV infusion after initial bolus doses 5
- Maximum reported doses in case studies have reached 11.6 grams over 12 days 2
- Patients with severe poisoning may require mechanical ventilation with PEEP in addition to atropine 6
- Monitor for signs of atropine toxicity: tachycardia, hyperthermia, delirium, urinary retention 4
Pediatric Dosing
- Initial dose: 0.02-0.05 mg/kg IV 3
- Maximum single dose: typically 2-3 mg 3
- Frequency: Repeat every 20-30 minutes as needed 3
- Caution: Children may be more susceptible to atropine toxicity but still require adequate dosing 3
Adjunctive Therapy
- Oximes (pralidoxime): 1-2 g IV initially, followed by 500 mg/hr continuous infusion 3
- Benzodiazepines: For seizure control and anxiety (midazolam 0.05-0.1 mg/kg or diazepam 0.2 mg/kg) 3
- Supportive care: Airway management, fluid resuscitation, vasopressor support if needed 2
Monitoring Parameters
- Heart rate and blood pressure: Target normalization of vital signs 4
- Respiratory status: Decreased secretions, improved oxygenation 2
- Mental status: Improvement in consciousness 2
- Pupil size: Resolution of miosis 3
Common Pitfalls
- Inadequate dosing: Insufficient atropine is a common error in severe poisoning; don't hesitate to give large doses when needed 2
- Premature discontinuation: Continue atropine until secretions are controlled 2
- Failure to recognize atropine allergies: Though rare, allergic reactions can occur 7
- Overreliance on oximes alone: Atropine remains the cornerstone of therapy 6