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    Atropine Dosing for Cholinesterase Inhibitor Toxicity

    Doses atropine for cholinesterase inhibitor toxicity (prescribed drugs, nerve gas, insecticides).
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    IMPORTANT

    This dosing tool is intended to assist with calculation, not to provide comprehensive or definitive drug information. Always double-check dosing of any drug and consult a pharmacist when necessary.

    INSTRUCTIONS

    • Use in patients with cholinergic toxicity to determine atropine bolus dose and continuous infusion rate.
    • Not for use in treating isolated bradycardia.
    • Not for use in AtroPen Atropine Auto-Injector dosing.
    • In the United States, the local Poison Control Center can be reached at 1-800-222-1222 to help guide management.
    When to Use
    Pearls/Pitfalls
    Why Use
    • Use for patients with cholinergic toxicity (causative agents are typically organophosphate compounds or carbamate, found in pesticides, or agents used in chemical warfare and terrorist attacks).
    • Many symptoms of cholinergic toxicity are recalled with the “SLUDGE and killer B’s” mnemonic:
      • Salivation.
      • Lacrimation.
      • Urination.
      • Defecation.
      • Gastric Emesis.
      • Bradycardia.
      • Bronchospasm.
      • Bronchorrhea.
    • This dosing guide was created to facilitate early and safe atropinization of the patient exhibiting signs of acute cholinergic toxicity.
    • May be used in patients exposed to either pesticide agents (more common) or agents of chemical warfare/terrorism.
    • Markers of atropinization vary, but the most clinically significant is resolution of bronchorrhea, as assessed by auscultation.
    • Large cumulative doses of atropine may be necessary to treat toxicity. Cases requiring hundreds to thousands of milligrams over the course of treatment have been reported (Hopmann 1974).

    Atropine is a competitive antagonist at muscarinic receptors and can reverse the deleterious or life-threatening symptoms of cholinergic toxicity, particularly bronchospasm and bronchorrhea.

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    Next Steps
    Evidence
    Creator Insights

    Advice

    • Patients suspected of cholinergic toxicity exhibiting signs of neuromuscular dysfunction should also be treated with pralidoxime (2-PAM).
    • Doses of atropine delivered intravenously should be given rapidly and in their entirety—slow administration or subtherapeutic doses have been associated with paradoxical bradycardia.

    Management

    Management of organophosphate / carbamate toxicity includes:

      • Prompt, safe, and thorough decontamination.
      • Early intubation for airway protection in severe cases.
        • Avoid succinylcholine for rapid sequence intubation, given prolonged duration of action in cholinergic poisonings.
      • Early atropinization.
      • Administration of pralidoxime.
      • Administration of benzodiazepines for seizure activity.
      • Admission to a higher level of care for close monitoring.

    Critical Actions

    Patients exposed to organophosphate or carbamate agents should be immediately decontaminated by removing all clothing and abundantly irrigating all exposed areas before initiating treatment.

    Formula

    • Initial dose:
      • Pediatric: 0.02 mg/kg, up to adult dose.
      • Adult, mild toxicity: 1-2 mg.
      • Adult, severe toxicity (hemodynamic compromise, unconsciousness): 3-5 mg.
    • Assess for atropinization every 5 minutes:
      • Clear lung exam on auscultation is the most important factor.
      • Additional factors: heart rate >80, systolic blood pressure >80.
    • If atropinization has not been achieved, double previous dose and reassess in another 5 minutes.
    • Repeat doubling every 5 minutes until atropinization achieved.
    • Once atropinization achieved, begin continuous infusion at an hourly rate of 10% of the sum of all doses necessary to achieve initial atropinization.
    • Titrate as necessary.

    Evidence Appraisal

    Very few trials have been conducted to assess different doses of atropine for cholinergic toxicity, and numerous recommended dosing regimens exist in the literature (Eddleston 2004). This calculator is based largely on the summation of expert opinions, although a randomized study found that a regimen of dose-doubling, followed by continuous infusion, resulted in decreased mortality and less atropine toxicity than a “conventional” bolus dosing protocol (Abedin 2012).

    Literature

    Dr. Lewis Goldfrank

    About the Creator

    Lewis Goldfrank, MD, FACEP, FAAEM, FAACT, FACMT, FACP, is the Herbert W. Adams Professor of Emergency Medicine at New York University. He is also the medical director of the New York City Poison Control Center. Dr. Goldfrank is perhaps best known as author and editor of the primary toxicology reference Goldfrank's Toxicologic Emergencies.

    To view Dr. Lewis Goldfrank's publications, visit PubMed

    Content Contributors
    • Philip DiSalvo, MD
    About the Creator
    Dr. Lewis Goldfrank
    Content Contributors
    • Philip DiSalvo, MD