OPC Poisoning

OPC Poisoning


       Organophosphorous poisoning and its treatment


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


       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


       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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