Anticholinesterase Mechanism and Comparison

Anticholinesterases inhibit the enzyme acetylcholinesterase (AChE), which breaks down acetylcholine (ACh). By preventing the breakdown of ACh, anticholinesterases prolong the action of ACh at cholinergic synapses.

Reversible anticholinesterases are structurally similar to ACh and bind to the active site of AChE, temporarily inhibiting its activity.

Organophosphorus compounds (OPs) are potent irreversible inhibitors of AChE. They form a stable covalent bond with the enzyme, leading to long-lasting inhibition.

Atropine is an anticholinergic drug that blocks the action of ACh at muscarinic receptors. This helps to counteract the excessive cholinergic effects of OP poisoning.

Glaucoma is a condition characterized by increased intraocular pressure. Drugs used in glaucoma management include miotics, beta-blockers, prostaglandin analogs, and carbonic anhydrase inhibitors.

A naturally occurring alkaloid, physostigmine is a tertiary amine. This means it can cross the blood-brain barrier and directly affect the central nervous system (CNS).

A synthetic derivative of physostigmine, neostigmine is a quaternary amine. It cannot cross the blood-brain barrier, so its effects are primarily on peripheral nerves, muscles, and organs.

A type of drug that mimics the action of acetylcholine (Ach) at the neuromuscular junction.

A class of drugs that block the breakdown of Ach, leading to increased Ach levels at the neuromuscular junction.

The aging process refers to the chemical reaction between organophosphates and acetylcholinesterase (AchE) becoming more stable and irreversible over time.

A syndrome characterized by increased saliva, tears, urination, sweating, diarrhea, and gastrointestinal upset. It's caused by the overstimulation of the parasympathetic nervous system.

Donepezil, galantamine, rivastigmine, and tacrine are cholinesterase inhibitors used to treat Alzheimer's disease. They work by increasing the levels of acetylcholine in the brain.

A critical difference in the application of anticholinesterases. Physostigmine crosses the blood-brain barrier, making it suitable for treating atropine poisoning, while neostigmine does not.

Organophosphates, like malathion and parathion, are insecticides that act as irreversible inhibitors of cholinesterase.

The primary use of edrophonium is to distinguish between myasthenia gravis and cholinergic crisis.

A group of symptoms caused by excessive acetylcholine (ACh) in the body, often due to organophosphate poisoning. Symptoms include diarrhea, urination, miosis (constricted pupils), bronchospasm, bradycardia, lacrimation (tearing), emesis (vomiting), salivation, and sweating. The mnemonic "DUMBBELLS" can help remember these symptoms.

A type of poisoning that affects the nervous system, characterized by muscle weakness, twitching, tremors, fasciculation, and potential paralysis. It is caused by the accumulation of acetylcholine (ACh) at the neuromuscular junction.

These drugs are used to treat organophosphate poisoning by reactivating acetylcholinesterase (AChE). They break the bond between the organophosphate and AChE, allowing AChE to function normally again. Examples include pralidoxime and obidoxime.

A common treatment for organophosphate poisoning, atropine antagonizes the effects of acetylcholine at muscarinic receptors, reducing the symptoms associated with the DUMBBELLS syndrome.