Drugs & Medication

A cholinesterase inhibitor or anticholinesterase is a chemical that inhibits a cholinesterase enzyme from breaking down acetylcholine, so increasing both the level and duration of action of the neurotransmitter acetylcholine.

Contents 1 Uses 2 Examples 2.1 reversible inhibitor 2.2 quasi-irreversible inhibitor 3 Effects

Uses

Anticholinesterases occur naturally as venoms and poisons, are used as weapons in the form of nerve agents, and are used medicinally to treat diseases such as myasthenia gravis and Alzheimer's disease, and as an antidote to anticholinergic poisoning. In myasthenia gravis, they are used to increase neuromuscular transmission.

Examples

reversible inhibitor

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

• Organophosphates
  • metrifonate
• Carbamates
  • physostigmine
    neostigmine
    pyridostigmine
    ambenonium
    demarcarium
    rivastigmine
• Phenanthrine derivatives
  • galantamine
• Piperidines
  • donepezil, also known as E2020
• Tacrine, also known as tetrahydroaminoacridine (THA')
• Edrophonium

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
  • cyclosarin
  • sarin
  • soman
  • tabun
  • VX
  • VE
  • VG
  • VM
  • diazinon
    malathion
    parathion
• Carbamates
  • aldicarb
    bendiocarb
    bufencarb
    carbaryl
    carbendazim
    carbetamide
    carbofuran
    chlorbufam
    chloropropham
    ethiofencarb
    formetanate
    methiocarb
    methomyl
    oxamyl
    phenmedipham
    pinmicarb
    pirimicarb
    propamocarb
    propham
    propoxur

Effects

Some major effects of anticholinesterase:

Actions on the autonomic nervous system, that is parasympathetic nervous system will cause bradycardia, hypotension, hypersecretion, bronchoconstriction, GIT hypermotility, and decrease intraocular pressure.

Actions on the neuromuscular junction will result in prolonged muscle contraction.