Medication Summary

Atropine was used as the sole treatment until oximes were developed; it is still used as the sole treatment in developing countries where oximes are not available. In the United States, oximes are used in mild cases; in more severe cases oximes are augmented by the use of atropine.

In cases of oral ingestion, activated charcoal in suspension may be used if the patient is seen within 30 minutes of ingestion.

Class Summary

These agents reactivate cholinesterases inactivated by phosphorylation due to exposure to organophosphates.

Pralidoxime chloride (Protopam, 2-PAM chloride)

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Strong nucleophilic agent that reactivates cholinesterase by reversing phosphorylation of serine hydroxyl group at active site of receptor membrane. Should be used within first 12-24 h and may need to be repeated over 2- to 3-week period. One patient in India, who ingested OPs in suicide attempt, required 92 g of pralidoxime over 23-d period.^[21]Effective against OP that is not irreversibly bound. Metabolized in liver and excreted in kidney. Early treatment most effective. Half-life 74-77 min. Not effective against carbamates. Should be used in severe OP toxicity.

Class Summary

These agents are used to reduce the clinical manifestations of organophosphate toxicity.

Atropine IV/IM (AtroPen)

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Antagonizes ACh at muscarinic receptor, leaving nicotinic receptors unaffected. Continue administration until excess muscarinic symptoms improve, which can be gauged by increased ease of breathing in conscious patient or improvement in ease of ventilation of intubated patient.

Follow-up

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Author

Frances M Dyro, MD Associate Professor of Neurology, New York Medical College; (Retired) Physician, Department of Neurology, Westchester Medical Center

Frances M Dyro, MD is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Neil A Busis, MD Chief of Neurology and Director of Neurodiagnostic Laboratory, UPMC Shadyside; Clinical Professor of Neurology and Director of Community Neurology, Department of Neurology, University of Pittsburgh Physicians

Neil A Busis, MD is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: American Academy of Neurology<br/>Serve(d) as a speaker or a member of a speakers bureau for: American Academy of Neurology<br/>Received income in an amount equal to or greater than $250 from: American Academy of Neurology.

Chief Editor

Stephen A Berman, MD, PhD, MBA Professor of Neurology, University of Central Florida College of Medicine

Stephen A Berman, MD, PhD, MBA is a member of the following medical societies: Alpha Omega Alpha, American Academy of Neurology, Phi Beta Kappa

Disclosure: Nothing to disclose.

Additional Contributors

Jonathan S Rutchik, MD, MPH, FACOEM Associate Clinical Professor, Division of Occupational Medicine, Department of Medicine, University of California, San Francisco, School of Medicine; Neurology, Environmental and Occupational Medicine Associates (www.neoma.com)

Jonathan S Rutchik, MD, MPH, FACOEM is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American College of Occupational and Environmental Medicine, International Parkinson and Movement Disorder Society, Society of Toxicology, Western Occupational and Environmental Medical Association

Disclosure: Nothing to disclose.