Which Indirect Cholinergic agonist is known to bind IRREVERSIBLY?

Echothiophate is indeed recognized as an indirect cholinergic agonist that binds irreversibly to the acetylcholinesterase enzyme. This irreversible binding leads to a prolonged increase in the levels of acetylcholine in the synaptic cleft, which enhances cholinergic signaling. Echothiophate functions primarily as a long-acting treatment for glaucoma and is classified as an organophosphate compound, which is distinctive due to its ability to form covalent bonds with the enzyme, resulting in a lasting effect compared to other indirect cholinergic agonists that bind reversibly.

In contrast, other options like neostigmine, edrophonium, and pyridostigmine act as reversible inhibitors of acetylcholinesterase. These drugs bind temporarily to the enzyme, allowing for the restoration of its activity after the drug is metabolized or displaced. This characteristic is crucial for medical uses where temporary enhancement of cholinergic transmission is needed, such as in the management of myasthenia gravis or for the reversal of neuromuscular blockade.

The irreversible nature of echothiophate's effect is significant in both therapeutic uses and potential toxicity, making it a unique agent among the others listed.