OPC Poisoning

OPC Poisoning

Content

•       Organophosphorous poisoning and its treatment

Objectives

At the end of this lecture, student will be able to

•       Explain organophophorous poisoning and its treatment

Choline esterase inhibitors (Anticholine esterases)

Irreversible choline esterase inhibitors

•       OPC

•       Useful: Di isopropyl fluorophosphate, metrifonate, echothiophate

•       Insecticides: Fenthion, malathion, sumithion, monocrotophos, octamethyl pyrophosphotetramide

Irreversible Anti ChE

•       Absorbed by all the routes

•       Cross BBB

•       Glaucoma: echothiophate

•       Toxicological importance

OPC Poisoning

Muscarinic effects

•       Eyes: Miosis, spasm of accomodation, head ache, conjunctival hyperemia

•        inhalation: bronchospasm, cough, increases secretions, tightness in chest

•       Ingestion: anorexia, nausea, vomitting, abdominal cramps, tenesmus and diarrhoea

•       Severe bronchospasm, pulm. edema - fatal

Nicotinic effects

•       Fasciculations, twitching, generalised weakness, depolarisation type paralysis

Central effects

•       Giddiness, anxiety, confusion, ataxia, hypotension, respiratory depression, convulsion, coma

•       Death – due to respiratory paralysis

Neurotoxic effects

•       Demyelination of nerve tracts in CNS & PNS

•       Permanent functional derrangements

•       Not related to ChE inhibition

•       Weakness, fatiguability, twitching, loss of tendon reflexes

Treatment of acute OPC Poisoning

•       Remove soiled clothes

•       Wash soiled skin/ eyes

•       Nurse in prone position

•       Clear mouth, throat

•       Insert airway/ intubate

•       Gastric lavage

•       Atropine in sufficient qty.

•       ChE activator: Pralidoxime (1-2 g)

•       Supportive measures: Oxygen, shock treatment

•       Convulsion: Diazepam

•       Vigilance for delayed toxicity

•       Note: Mouth to mouth respiration to be avoided

Summary

•       Cholinergic drugs stimulate effector cells innervated by cholinergic nerves

•       Cholinergic drugs: Ester of choline, Cholinomimetic alkaloids, Choline esterase inhibitors (Anticholine esterase)

•       Acetylcholine actions - mostly inhibitory; stimulatory on digestion and exocrine glands

•       Pralidoxime is the antidote for OPC poisoning

 

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