Echothiophate (Phospholine) is an irreversible acetylcholinesterase inhibitor.

[1] It is used as an ocular antihypertensive in the treatment of open angle glaucoma and, in some cases, accommodative esotropia.

Because of the very slow rate at which echothiophate is hydrolyzed by cholinesterase, its effects can last a week or more.

Wyeth Pharmaceuticals stopped manufacturing echothiophate iodide in the US in 2003.

][citation needed] 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.