Organophosphates Medication

Updated: Nov 29, 2016
  • Author: Frances M Dyro, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Medication

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.

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Antidotes

Class Summary

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

Pralidoxime chloride (Protopam, 2-PAM chloride)

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.

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Anticholinergic agents

Class Summary

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

Atropine IV/IM (AtroPen)

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.

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