Pediatric Organophosphates Toxicity Medication
- Author: William Freudenthal, MD; Chief Editor: Timothy E Corden, MD more...
Anticholinergic agents are important for controlling the life-threatening effects of organophosphate exposure. Initiate atropine therapy early to control secretions, bronchoconstriction, bronchospasm, and GI toxicity. Pralidoxime (2-PAM) is an oxime that reactivates cholinesterase, restoring respiratory and skeletal muscle strength. 2-PAM does not cross the blood-brain barrier; hence, the central effects are not reversed.
These agents are thought to work centrally by suppressing conduction in the vestibular cerebellar pathways. They may have an inhibitory effect on the parasympathetic nervous system. Anticholinergic agents also improve conduction through the AV node by reducing vagal tone by means of muscarinic receptor blockade.
Competitive antagonist of acetylcholine and other muscarinic agonists. Competes for common binding site on muscarinic receptor. Used to treat GI, pulmonary, and upper airway symptoms after known or suspected organophosphate exposure. Administer until cholinergic signs reverse. Large doses may be needed.
These medications are used as antidotes to reverse the inhibition of acetylcholinesterase (AChE). The effectiveness of oxime compounds is attributed to their 2-formyl-1-methylpyridinium ions.
Nucleophilic agent that reactivates phosphorylated AChE by binding to organophosphate molecule. Used to treat muscle weakness and respiratory muscle weakness in known or suspected exposure. Must be administered within 24 h, before organophosphate-cholinesterase bond ages. Earlier administered, better result. Effects should occur within 20-30 min.
Because it does not substantially relieve respiratory center depression or decrease muscarinic effects of AChE poisoning, concomitantly administer atropine to block effects of organophosphate poison on these areas. Signs of atropinization might occur earlier with addition of 2-PAM.
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