Acetylcholinesterase inhibitor





An acetylcholinesterase inhibitor (often abbreviated AChEI) or anti-cholinesterase is a chemical that inhibits the cholinesterase enzyme from breaking down acetylcholine, increasing both the level and duration of action of the neurotransmitter acetylcholine.

Uses
Acetylcholinesterase inhibitors:


 * Occur naturally as venoms and poisons
 * Are used as weapons in the form of nerve agents
 * Are used medicinally:
 * To treat myasthenia gravis. In myasthenia gravis, they are used to increase neuromuscular transmission.
 * To treat Glaucoma
 * To treat Alzheimer's disease
 * To treat Lewy Body Dementia
 * As an antidote to anticholinergic poisoning

Reversible inhibitor
Compounds which function as reversible competitive or noncompetitive inhibitors of cholinesterase are those most likely to have therapeutic uses. These include:


 * Some organophosphates not listed under "Irreversible" below
 * Delta9-tetrahydrocannabinol (THC)
 * Carbamates
 * Physostigmine
 * Neostigmine
 * Pyridostigmine
 * Ambenonium
 * Demarcarium
 * Rivastigmine
 * Phenanthrene derivatives
 * Galantamine
 * Piperidines
 * Donepezil, also known as E2020
 * Tacrine, also known as tetrahydroaminoacridine (THA')
 * Edrophonium
 * Huperzine A
 * Ladostigil
 * Ungeremine

Quasi-irreversible inhibitor
Compounds which function as quasi-irreversible inhibitors of cholinesterase are those most likely to have use as chemical weapons or pesticides. These include:


 * Organophosphates
 * Echothiophate
 * Diisopropyl fluorophosphate
 * Cadusafos
 * Cyclosarin
 * Dichlorvos
 * Dimethoate
 * Metrifonate (irreversible)
 * Sarin
 * Soman
 * Tabun
 * VX
 * VE
 * VG
 * VM
 * Diazinon
 * Malathion
 * Parathion


 * Carbamates
 * Aldicarb
 * Bendiocarb
 * Bufencarb
 * Carbaryl
 * Carbendazim
 * Carbetamide
 * Carbofuran
 * Carbosulfan
 * Chlorbufam
 * Chloropropham
 * Ethiofencarb
 * Formetanate
 * Methiocarb
 * Methomyl
 * Oxamyl
 * Phenmedipham
 * Pinmicarb
 * Pirimicarb
 * Propamocarb
 * Propham
 * Propoxur

Natural Compounds

 * Huperzine A
 * Galantamine
 * Onchidal
 * Coumarins

Effects
Some major effects of cholinesterase inhibitors:

Administration of reversible cholinoesterase inhibitors is contraindicated with those that have urinary retention due to obstruction.
 * Actions on the autonomic nervous system, that is parasympathetic nervous system will cause bradycardia, hypotension, hypersecretion, bronchoconstriction, GI tract hypermotility, and decrease intraocular pressure.
 * SLUDGE syndrome.
 * Actions on the neuromuscular junction will result in prolonged muscle contraction.

Titration phase
When used in the central nervous system to alleviate neurological symptoms, such as rivastigmine in Alzheimer's disease, all cholinesterase inhibitors require doses to be increased gradually over several weeks, and this is usually referred to as the titration phase.