DIISOPROPYL FLUOROPHOSPHATE

Toxicity

Signs of overdose include increased sweating, loss of bladder control, muscle weakness, nausea, vomiting, diarrhea, or stomach cramps or pain, shortness of breath, tightness in chest, or wheezing, slow or irregular heartbeat, unusual tiredness or weakness, watering of mouth.

Chemical properties

Colourless Liquid

Originator

Floropryl,MSD,US,1949

The Uses of DIISOPROPYL FLUOROPHOSPHATE

Diisopropyl Fluorophosphate is a potent inhibitor of serine proteases such as trypsin and chymotrypsin, and of acetylcholinesterase. Diisopropyl fluorophosphate is a very potent neurotoxin.

The Uses of DIISOPROPYL FLUOROPHOSPHATE

DFP served as a basis for developing nerve gases during World War II. It is not used as a nerve gas; it is employed as a pharmacology tool to investigate the toxic properties of nerve gases. It is applied as a miotic and in ophthalmic use.

Background

An irreversible cholinesterase inhibitor with actions similar to those of echothiophate. It is a powerful miotic used mainly in the treatment of glaucoma. Its vapor is highly toxic and it is recommended that only solutions in arachis oil be used therapeutically. (From Martindale, The Extra Pharmacopoeia, 29th ed, p1330)

Indications

For use in the eye to treat certain types of glaucoma and other eye conditions, such as accommodative esotropia.

Definition

ChEBI: Diisopropyl fluorophosphate is a dialkyl phosphate.

Manufacturing Process

212 lb (3.54 lb-mols) of isopropanol containing less than 0.2 wt % of water was cooled with brine to -5°C in a jacketed reactor. 160 lb (1.16 lb-mols) of phosphorus trichloride was gradually added to the isopropanol with cooling and stirring during a period of 4 hours. The temperature of the reaction was not allowed to exceed 12°C and the system was maintained under slight negative pressure (about 700 mm) to remove undesirable vapors.
After completion of the addition, the mixture was stirred for ? hour and then subjected to a pressure of 12 to 100 mm of mercury. Chlorine was then passed into the crude reaction product at a rate of 12 lb/hr, the temperature of the reaction being kept below 12°C by brine cooling. The end of the reaction was indicated by a temperature drop which occurred after a total of 122 lb of chlorine (1.72 lb-mols, 48% excess) was used.
To remove excess chlorine, hydrogen chloride and isopropyl chloride, the wellstirred mixture was subjected to a pressure of 12 to 100 mm of mercury for 2 hours. The temperature was gradually raised to 20°C during this time by passing steam into the jacket of the reactor. 10 gallons of benzene was then added and distilled off under reduced pressure, gradually raising thetemperature of the reaction mixture to 30°C. The last traces of hydrogen chloride were removed by adding an additional 10 gallons of benzene which was distilled off under reduced pressure at reactor temperatures not exceeding 50°C. The total time required for the removal of the volatile acid components of the reaction mixture was 4 hours.
The mixture was then cooled to 20°C and 19 gallons of benzene was added. This was followed by the introduction of 123.5 lb (2.80 lb-mols) of dry powdered sodium fluoride (95% pure). The mixture was stirred and heated to the refluxing temperature in a period of 1 hour and held at this temperature (95° to 98°C) for 4 hours. The product obtained was cooled and filtered to yield a filter cake which was washed with three 5-gallon portions of benzene. The filtrate and washing were then combined and distilled under reduced pressure. There was obtained 158 lb (74% yield of theory based on PCl3) of diisopropyl fluorophosphate, BP 62°C at 9 mm and 46°C at 5 mm.

brand name

Floropryl(Merck).

Therapeutic Function

Cholinergic (ophthalmic)

Synthesis Reference(s)

Canadian Journal of Chemistry, 44, p. 501, 1966 DOI: 10.1139/v66-067

General Description

Oily liquid. Clear, colorless or faintly yellow liquid. DIISOPROPYL FLUOROPHOSPHATE is used as a research tool in neuroscience for its ability to inhibit cholinesterase (by phosphorylation) on an acute/sub-acute basis and to produce a delayed neuropathy. An insecticide. Used in Germany as a basis for "nerve gases".

Air & Water Reactions

Forms hydrogen fluoride in presence of moisture; decomposes in water at pH about 2.5.

Reactivity Profile

Organophosphates, such as DIISOPROPYL FLUOROPHOSPHATE, are susceptible to formation of highly toxic and flammable phosphine gas in the presence of strong reducing agents such as hydrides. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides.

Health Hazard

This is an organophosphate pesticide. Extremely toxic: probable oral lethal dose in humans is 5-50 mg/kg, between 7 drops and 1 teaspoonful for 70 kg person (150 lb.). The material is a cholinesterase inactivator. Even traces of the vapor cause pinpoint pupils.

Health Hazard

DFP is a highly toxic organophosphate. Its chemical structure is similar to that of sarin and soman. It is a potent inhibitor of acetylcholinesterase, and its toxic actions are lower but similar to those of sarin and soman. Subcutaneous administration of 1.5 mg/kg causedcholinergicsymptomsinrats,inducing a progressive dose-related necrosis (Dettbarn 1984). DFP administered to rats produced muscle fiber discharges from the peripheral nerves as well as from the central nervous system (Clinton et al. 1988). This was significantly reduced when the animals were pretreatedwithatropinemethylnitrate,ketamine, or phenytoin.
In humans, exposure to its vapors at 1.5 ppm concentration in air for 10 minutes may produce headache and constriction of the pupil of the eye.
LD50 value, oral(rabbits): 10 mg/kg (NIOSH 1986)
LD50 value, subcutaneous (rats): 2 mg/kg (NIOSH 1986).

Fire Hazard

May burn but will not ignite readily. Container may explode in heat of fire. Fire and runoff from fire control water may produce irritating or poisonous gases. Forms hydrogen fluoride in presence of moisture; decomposes in water at pH about 2.5. Keep away from sources of heat. Anhydrous compounds or oil solutions are stable in glass containers at room temperature.

Biochem/physiol Actions

Potent inhibitor of serine proteases such as trypsin and chymotrypsin, and of acetylcholinesterase; also inhibits cathepsin G, cholinesterase, coagulation factor Xa, leucocyte elastase, pancreatic elastase, tissue kallikrein, plasmin, subtilisin, and thrombin. Inhibition of acetylcholinesterase makes this compound especially toxic. Inhibits apoptosis induced by ricin and bacterial toxins.

Pharmacokinetics

Isoflurophate is used as ocular drops in the treatment of chronic glaucoma. Isoflurophate is an organophosphorus compound that acts as an irreversible cholinesterase inhibitor. As such, it displays parasympathomimetic effects. Isoflurophate is used in the eye to treat certain types of glaucoma and other eye conditions, such as accommodative esotropia. They may also be used in the diagnosis of certain eye conditions, such as accommodative esotropia. Isoflurophate damages the acetylcholinesterase enzyme and is therefore irreversible, however, pralidoxime can displace organophosphates such as isoflurophate from acetylcholinesterase, but only if administered before isoflurophate damages (alkylates) the enzyme.

Metabolism

Not Available

Waste Disposal

It is dissolved in a combustible solvent and burned in a chemical incinerator. It may be destroyed by treating with molten metal at 800-1000°C (1472-1832°F). It may be decomposed by treatment with dilute acid. Care should be taken, as highly toxic HF may be generated.