Echothiophate is a parasympathomimetic and a phosphorothioate. It is an acetylcholinesterase inhibitor

Acetylcholinesterase inhibitor

An acetylcholinesterase inhibitor or anti-cholinesterase is a chemical that inhibits the cholinesterase enzyme from breaking down acetylcholine, increasing both the level and duration of action of the neurotransmitter acetylcholine.- Uses :Acetylcholinesterase inhibitors:* Occur naturally as...

.

Uses

It is used as an ocular antihypertensive in the treatment of chronic glaucoma

Glaucoma

Glaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...

 and, in some cases, accommodative esotropia

Esotropia

Esotropia is a form of strabismus, or "squint", in which one or both eyes turns inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance...

. It is available under several trade names such as Phospholine Iodide (Wyeth-Ayerst).

Echothiophate binds irreversibly to cholinesterase

Cholinesterase

In biochemistry, cholinesterase is a family of enzymes that catalyze the hydrolysis of the neurotransmitter acetylcholine into choline and acetic acid, a reaction necessary to allow a cholinergic neuron to return to its resting state after activation.-Types:...

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

Adverse drug reaction

An adverse drug reaction is an expression that describes harm associated with the use of given medications at a normal dosage. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs...

s include muscle spasm and other systemic effects.

Shortage

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 After contacting the American Academy of Ophthalmology (AAO), Wyeth rescinded their decision and, according to AAO public relations representative Michelle Stephens, the AAO and Wyeth were in talks for about a year about manufacturing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.

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

Chemistry

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

H.M. Fitch, (1959).