Organophosphate (OP)
Definition
A class of insecticides (monocrotophos, chlorpyrifos, methyl parathion, dichlorvos, phorate) that inhibit acetylcholinesterase, producing the cholinergic toxidrome. The dominant suicidal poison in Maharashtra Vidarbha, Andhra-Telangana and northern Karnataka.
- Mechanism
- Irreversibly phosphorylate acetylcholinesterase at the active-site serine
- Poisoning signature
- Cholinergic toxidrome (overstimulation of nervous system)
- Drug class
- Insecticides and pesticides
- Common in certain regions
- Among the most common suicidal poisons in parts of Maharashtra (Vidarbha), Andhra-Telangana, and northern Karnataka
Common questions
What do organophosphates do to the body?+
Organophosphates block an enzyme called acetylcholinesterase, which normally breaks down a signaling chemical in the nervous system. When the enzyme is blocked, this chemical builds up, overstimulating nerves and muscles. The result is the cholinergic toxidrome, a characteristic pattern of poisoning symptoms.
Can organophosphate poisoning be treated?+
Yes. The standard antidote is a combination of atropine and pralidoxime (PAM). Atropine blocks the effects of the excess neurotransmitter, while pralidoxime can reverse some of the damage to the acetylcholinesterase enzyme, but only if given early.
Which organophosphates are commonly encountered?+
Common examples include monocrotophos, chlorpyrifos, parathion, malathion, methyl parathion, dimethoate, dichlorvos, and phorate. Most are used as insecticides and pesticides in agriculture.
Related terms
- AChE / BChE
- Acetylcholinesterase (RBC membrane bound, true cholinesterase) and butyrylcholinesterase (plasma, pseudo-cholinesterase). Both depressed in OP and carbamate exposure; plasma BChE falls first and...
- Aluminium Phosphide
- A solid grey-green pellet fumigant sold as Celphos, Quickphos or Sulfo-Carb for stored grain. On contact with moisture it releases phosphine gas,...
- Aluminium Phosphide (AlP)
- Solid grain-fumigant rodenticide sold as Celphos, Quickphos, Sulfas tablets. On contact with moisture or stomach acid, releases phosphine (PH3) gas, which blocks...
- Anupam Verma Committee
- An expert committee constituted by the Ministry of Agriculture in 2013 to review 66 pesticides already banned in other countries but still...
- Carbamate
- Carbamic-acid ester insecticides (carbaryl, carbofuran, propoxur, aldicarb). Reversibly inhibit acetylcholinesterase by carbamylating the active-site serine; spontaneous decarbamylation makes oximes unnecessary and sometimes...
- Cerbera Odollam
- The yellow oleander or 'suicide tree', a Kerala coastal tree whose seed contains cardiac glycosides (cerberin, thevetin). Dominant in Kannur and Kasaragod...
- Cleistanthus Collinus
- Oduvanthalai, a deciduous shrub of the Tamil Nadu Salem-Erode belt whose leaf decoction causes hypokalaemia, distal renal tubular acidosis and ARDS. Peak...
- Ellman Method
- Standard spectrophotometric cholinesterase assay. Acetylthiocholine substrate plus 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) yields a yellow 5-thio-2-nitrobenzoate anion read at 412 nm. The rate of...
- NCRB ADSI
- Accidental Deaths and Suicides in India, the annual statistical volume published by the National Crime Records Bureau under the Ministry of Home...
- Organochlorine (OC)
- Chlorinated hydrocarbon insecticides (DDT, BHC/lindane, endosulfan, dicofol, aldrin, dieldrin). Highly lipophilic, neurotoxic via voltage-gated sodium channel disruption, and persistent in fat and...
- Pyrethroid
- Synthetic analogues of natural pyrethrins (deltamethrin, cypermethrin, permethrin, fenvalerate). Act on voltage-gated sodium channels like OC but break down quickly in mammals,...
- QuEChERS
- Quick, Easy, Cheap, Effective, Rugged and Safe sample-prep protocol for pesticide residues. Acetonitrile extraction, MgSO4 + NaCl partition, dispersive SPE clean-up with...
Explained in these topics
- Insecticides and Pesticides: Organochlorines, Organophosphates and CarbamatesPhosphate or thiophosphate esters (parathion, malathion, monocrotophos, dimethoate, chlorpyrifos, dichlorvos). Irreversibly inhibit acetylcholinesterase by pho...
- Poisoning Trends and Patterns in IndiaA class of insecticides (monocrotophos, chlorpyrifos, methyl parathion, dichlorvos, phorate) that inhibit acetylcholinesterase, producing the cholinergic toxid...