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Clinical data
Trade namesChlorophos (and many others)[1]Trichlorfon; Phosphonic acid, (2,2,2-trichloro-1-hydroxyethyl)-, dimethyl ester; (2,2,2-Trichloro-1-hydroxyethyl) dimethylphosphonate; Agroforotox; Anthon; Chlorofos; Chloroftalm; Chlorophos; Chlorophthalm; Chloroxyphos; Combot; Dimethyl (trichlorohydroxyethyl)phosphonate; Dimethyl (1-hydroxy-2,2,2-trichloroethyl)phosphonate; Dimethyl (2,2,2-trichloro-1-hydroxyethyl)phosphonate; Dipterax; Dipterex; Dipterex 50; Diptevur; Ditrifon; Dylox; Dyrex; Dyvon; DEP; DEP (Pesticide); DETF; ENT 19,763; Flibol E; Fliegenteller; Forotox; Foschlor; Foschlor R; Foschlor R 50; Hypodermacid; Loisol; Masoten; Mazoten; Methyl Chlorophos; Metifonate; Metriphonate; Neguron; Neguvon; O,O-Dimethyl (1-hydroxy-2,2,2-trichloroethyl)phosphonate; O,O-Dimethyl (2,2,2-trichloro-1-hydroxyethyl)phosphonate; O,O-Dimethyl (2,2,2-trichlorohydroxyethyl)phosphonate; Phoschlor; Phoschlor R50; Polfoschlor; Ricifon; Ritsifon; Soldep; Sotipox; Trichlorphon; Trichlorphon FN; Tugon; Volfartol; Votexit; Wotexit; WEC 50; (1-Hydroxy-2,2,2-trichloroethyl)phosphonic acid, dimethyl ester; (2,2,2-Trichloro-1-hydroxyethyl)phosphonate, dimethyl ester; (2,2,2-Trichloro-1-hydroxyethyl)phosphonic acid dimethyl ester; Bayer L 1359; Bilarcil; Bovinox; Briton; BAY 15922; Cekufon; Chlorophosciclosom; Clorofos; Danex; Dimethoxy-(2,2,2-trichloro-1-hydroxyethyl)phosphine oxide; Equino-Aid; Foschlorem; Khloroftalm; NCI-C54831; O,O-Dimethyl (1-hydroxy-2,2,2-trichloroethyl)phosphate; O,O-Dimethyl-(1-hydroxy-2,2,2-trichloraethyl)phosphosaeure ester; O,O-Dimethyl-(1-hydroxy-2,2,2-trichlorathyl)-phosphat; O,O-Dimethyl-(2,2,2-trichloor-1-hydroxy-ethyl)-fosfonaat; O,O-Dimethyl-(2,2,2-trichlor-1-hydroxy-aethyl)phosphonat; O,O-Dimetil-(2,2,2-tricloro-1-idrossi-etil)-fosfonato; Phosphonic acid, (1-hydroxy-2,2,2-trichloroethyl)-, dimethyl ester; Proxol; Trichloorfon; Trichlorofon; Trichlorophon; Trinex; 1-Hydroxy-2,2,2-trichloro-ethyle phosphonate de dimethyle; Bay-L 1359; Briten; Denkaphon; Dipterex WP 80; Ertefon; OMS 800; Zeltivar; Onefon; O,O-Dimethyl-1-oxy-2,2,2-trichloroethyl phosphonate;Trichlorfon; 1-Hydroxy-2,2,2-trichloroethylphosphonate-O,O-dimethyl ester; Phosphonic acid, P-(2,2,2-trichloro-1-hydroxyethyl)-, dimethyl ester; Chlorak; Dimetox; Dioxaphos[2]
Other namesTrichlorphon
AHFS/Drugs.comInternational Drug Names
ATC code
Pharmacokinetic data
Elimination half-life3 hours
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.000.137 Edit this at Wikidata
Chemical and physical data
Molar mass257.43 g·mol−1
3D model (JSmol)
ChiralityRacemic mixture
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Metrifonate (INN) or trichlorfon (USAN) is an irreversible organophosphate acetylcholinesterase inhibitor.[3] It is a prodrug which is activated non-enzymatically into the active agent dichlorvos.

It is used as an insecticide.

It can be used to treat schistosomiasis[4] caused by Schistoma haematobium,[5] but is no longer commercially available.[6]

It has been proposed for use in treatment of Alzheimer's disease, but use for that purpose is not currently recommended.[7]

Bans and restrictions[edit]

In the United States, trichlorfon/metrifonate may only be used on nonfood and nonfeed sites.[8] Bayer, the registrant, voluntarily cancelled the use on sod farms and residential lawns. Bayer also voluntarily canceled all food, feed and field crop registrations.

Trichlorfon/metrifonate was banned in the EU in 2008 (Regulation (EC) 689/2008) and in Brazil in 2010.[9]

Trichlorfon/metrifonate was banned in Argentina in 2018,[10] noting that trichlorvon converts to dichlorvos by metabolism in plants, as well as by biodegradation of the soil.

Trichlorfon/metrifonate was banned in New Zealand in 2011.[11]

Trichlorfon/metrifonate was banned in India from 2020.[12]


  1. ^ "Trichlorfon". Haz-Map. U.S. National Library of Medicine. August 2015. Retrieved 2015-10-13.
  2. ^ "Metrifonate". U.S. National Institute of Standards and Technology. Retrieved 2016-09-04.
  3. ^ "NLH - Neurological Conditions - Metrifonate for Alzheimer's disease". Archived from the original on 2009-07-19.
  4. ^ "Monographs: Pharmaceutical substances: Metrifonate (Metrifonatum)". The International Pharmacopoeia Fourth Edition. WHO. Retrieved 2015-10-20. (dead link 31 January 2019)
  5. ^ "Helminths: Schistosomiasis: Metrifonate". WHO Model Prescribing Information: Drugs Used in Parasitic Diseases - Second Edition. WHO. 1995. Retrieved 2015-10-20.
  6. ^ Ross AG, Bartley PB, Sleigh AC, Olds GR, Li Y, Williams GM, McManus DP (April 2002). "Schistosomiasis" (PDF). The New England Journal of Medicine. 346 (16): 1212–20. doi:10.1056/NEJMra012396. PMID 11961151.
  7. ^ López-Arrieta JM, Schneider L (April 2006). López-Arrieta J (ed.). "Metrifonate for Alzheimer's disease". The Cochrane Database of Systematic Reviews (2): CD003155. doi:10.1002/14651858.CD003155.pub3. PMID 16625573.
  8. ^ "Reregistration Eligibility Decision Trichlorfon" (PDF). Retrieved 2018-08-09.
  9. ^ "Decision Guidance Document Trichlorfon - Rotterdam Convention" (PDF). Retrieved 2018-08-09.
  10. ^ "Argentina bans dichlorvos and trichlorfon". Retrieved 2018-08-09.
  11. ^ "New Zealand bans trichlorfon". Retrieved 2018-08-09.
  12. ^ "Banned Pesticides in India". 2018-01-17. Retrieved 2018-08-09.