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Echothiophate iodide.svg
Systematic (IUPAC) name
2-(Diethoxyphosphorylsulfanyl)ethyl-N,N,N-trimethylazanium iodide
Clinical data
Trade names Phospholine
Legal status
Routes Topical (eye drops)
CAS number 6736-03-4 YesY
ATC code S01EB03
PubChem CID 10547
DrugBank DB01057
ChemSpider 10107 YesY
KEGG D02193 YesY
ChEBI CHEBI:59849 YesY
Chemical data
Formula C9H23INO3PS 
Molecular mass 383.228 g/mol
 N (what is this?)  (verify)

Echothiophate (Phospholine) is a parasympathomimetic and a phosphorothioate. It is an irreversible acetylcholinesterase inhibitor.[1]


It is used as an ocular antihypertensive in the treatment of chronic glaucoma and, in some cases, accommodative esotropia. It is available under several trade names such as Phospholine Iodide (Wyeth-Ayerst).

Echothiophate binds irreversibly to cholinesterase. Because of the very slow rate at which echothiophate is hydrolyzed by cholinesterase, its effects can last a week or more. Adverse effects include muscle spasm and other systemic effects.

Mechanism of action[edit]

It covalently binds by its phosphate group to serine group at the active site of the cholinesterase. Once bound, the enzyme is permanently inactive and the cell has to make new enzymes.


Wyeth Pharmaceuticals stopped manufacturing echothiophate iodide in the US in 2003. After contacting the American Academy of Ophthalmology (AAO), Wyeth rescinded their decision and, according to AAO public relations representative Michelle Stephens, the AAO and Wyeth were in talks for about a year about manufacturing it. [2]

In the meantime, a worldwide shortage of the drug has occurred.


Echothiophate is made by reacting diethylchlorophosphoric acid with 2-dimethylaminoethylmercaptan, giving S-(2-dimethylaminoethyl)-O,O-diethylthiophosphate, which is alkylated by methyl iodide, forming echothiophate.[3]

Echothiophate synthesis.png