Chlorfenvinphos is an antiparasitic active ingredient used in veterinary medicine in dogs and livestock against external parasites (lice, mites, fleas, flies, ticks, etc.). It was also used against agricultural and household pests. It belongs to the chemical class of the organophosphates.
Common name: CHLORFENVINPHOS
Other names: CHLORFENVINFOS
Chemical class: organophosphate
EFFICACY AGAINST PARASITES
Type of action: Broad spectrum contact, non systemic ectoparasiticide: insecticide, acaricide, tickicide, louisicide, larvicide
Main veterinary parasites controlled: flies, lice, fleas, mosquitoes, ticks, mites, fly maggots (cutaneous myiases) etc.
Efficacy against a specific parasite depends on the delivery form and on the dose administered.
Click here for general information on features and characteristics of PARASITICIDES.
Chlorfenvinphos is a contact insecticide and acaricide without systemic effect that belongs to the chemical class of the organophosphates. It is effective against several external parasites of livestock and dogs (flies, lice, mites, ticks). It is not effective against internal parasites.
Chlorfenvinphos was abundantly used in the past both in livestock and pets but has been widely replaced in most countries by less toxic compounds. Nowadays it remains available in a few places mainly for spraying or dipping or as larvicidal dressing for livestock and dogs, often mixed with synthetic pyrethroids.
It is also used against agricultural and household pests.
However, resistance to all organophosphates is already very frequent worldwide, particularly in cattle ticks, houseflies, mosquitoes, fleas, blowfly strike, etc.
The table below indicates some usual dosing recommendations for chlorfenvinphos issued by manufacturers or documented in the scientific literature. They may not be approved in some countries.
|Dosing recommendations for CHLORFENVINPHOS
|Delivery||Parasites||Dose (against chlorfenvinphos-susceptible parasites)
|Topical (bath)||Fleas, ticks lice, mites||200-400 ppm (=mg/L) in the wash, dep. on indications|
|Topical (overspray)||Buffalo flies||4000 ppm, 50 mL wash/150 kg liveweight|
|Topical (spray, dip)||Flies, ticks, lice||300-550 ppm (=mg/L) in the wash, dep. on indications|
|Topical (spray, dip)||Flies, ticks, lice||300-550 ppm (=mg/L) in the wash, dep. on indications|
|Topical (spray, dip)||Flies, ticks, lice||300-550 ppm (=mg/L) in the wash, dep. o indications|
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Dosing recommendations for antiparasitics depend on national regulations. National regulatory authorities determine whether a product is approved for a given indication, i.e. use on a particular host at a specific dose and against a specific parasite. Check the labels of the products available in your country for specific information on approved indications.
Oral LD50, rat, acute*: 9.6 to 39 mg/kg
Dermal LD50, rat, acute*: 30 to 108 mg/kg
* These values refer to the active ingredient. Toxicity has to be determined for each formulation as well. Formulations are usually significantly less toxic than the active ingredients.
MRL (maximum residue limit) set for animal tissues (e.g. beef, mutton pork or chicken)*:
- CODEX: No
- EU: Yes
- USA: No
- AUS: Yes
* This information is an indicator of the acceptance of an active ingredient by the most influential regulatory bodies for use on livestock. MRL's for animal tissues may be set also for agricultural pesticides that are not approved for use on animals but are used on commodities fed to animals. A MRL may be also set in the form of an IMPORT TOLERANCE for active ingredients not approved in a particular country but approved for imported animal commodities.
Withholding periods for meat, milk, eggs, etc. depend on delivery form, dose and national regulations. Check the product label in your country.
Learn more about chlorfenvinphos safety (poisoning, intoxication, overdose, antidote, symptoms, etc.).
General safety information for antiparasitics is available in specific articles in this site (click to visit):
- General safety of antiparasitics for domestic animals
- General safety of antiparasitics for humans
- General safety of antiparasitics for the environment
Never use agricultural or hygiene products with this or any other active ingredient on livestock or pets, even if there are veterinary products with this same active ingredient approved for use on animals. The formulations for agricultural or hygiene use are different and may be toxic for livestock or pets.
It is obvious that veterinary products are not intended for and should never be used on humans!!!>
MARKETING & USAGE
Decade of introduction: 1960
Introduced by: SHELL (→ FORT DODGE → ZOETIS), CIBA-GEIGY (→ NOVARTIS )
Some original brands: SUPONA, STELADONE, SAPECRON
Patent: Expired (particular formulations may be still patent-protected)
Use in LIVESTOCK: Yes, scarce, declining as all organophosphates
Use in HORSES: Yes, very scarce and declining as all organophosphates
Use in DOGS and CATS: Yes, moderate, declining as all organophosphates
Main delivery forms:
Use in human medicine: No
Use in public/domestic hygiene: Yes
Use in agriculture: Yes
Generics available: Yes, a few
In livestock & horses: Yes, as for all organophosphates: very frequent worldwide in such species as cattle ticks (Boophilus spp), horn flies (Haematobia irritans), sheep lice (Damalinia ovis), poultry mites (Dermanyssus gallinae), houseflies (Musca domestica), mosquitoes
In pets: Yes, quite frequent worldwide in dog and cat fleas (Ctenocephalides spp)
Visit also the section in this site about parasite resistance to antiparasitics and more specifically to organophosphates.
Clorfenvinphos is a classical, veteran parasiticide belonging to the organophosphates. It has been used a lot in the 1960's to 1990s, both in livestock and pets.
In livestock it is still used In cattle in concentrates for dipping and spraying in some countries where cattle ticks are a problem, and in dressings against fly maggots. Its use as a tickicide declined in the 1980s - 1990's after the introduction of synthetic pyrethroids, which are safer for livestock, operators and wild birds, more effective against biting flies, and easier to handle in plunge dips, because they do not strip.
In dogs and cats chlorfenvinphos is still used in shampoos, soaps, baths, sprays and the like, but its use has strongly declined after the introduction of more modern and safer flea and tick control spot-ons (= pipettes) and tablets.
In the USA all the uses of chlorfenvinphos were cancelled in 1991. In the 2000s registration in several countries was not renewed (e.g. SUPONA in the EU) due to insufficient data: manufacturers were not willing to invest in new studies for an "old" organophosphate. NOVARTIS e.g. divested all its organophosphate products around the year 2000, including those with chlorfenvinphos: they were sold to ZAGRO. It has also been banned in the EU.
Efficacy of chlorfenvinphos
As most organophosphates clorfenvinphos is a broad-spectrum insecticide and acaricide. Clorfenvinphos is particularly effective against all tick species that affect livestock, both single-host ticks (e.g. Boophilus spp.) as well as two-host and multi-host ticks (e.g. Amblyomma spp, Dermacentor spp, Haemaphysalis spp, Hyalomma spp, Rhipicephalus spp, etc.).
However, resistance of important veterinary parasites to all organophosphates, including chlorfenvinphos is widespread, especially in cattle ticks (Boophilus spp), horn flies (Haematobia irritans), sheep lice (Damalinia ovis), poultry mites (Dermanyssus gallinae), mosquitoes, dog and cat fleas (Ctenocephalides spp) and houseflies (Musca domestica). As a consequence, products with this active ingredient may not achieve the expected efficacy in many places. The same applies to all other organophosphates. This is also a reason for their progressive replacement with newer active active ingredients with a different mode of action.
Pharmacokinetics of chlorfenvinphos
Percutaneous absorption (i.e. through the skin) of topically administered chlorfenvinphos depends on the animal species, the administered dose, and the extension of the treated body surface. Studies in human volunteers showed that up to 30% of the topically administered dose was absorbed through the skin. Treated animals can ingest chlorfenvinphos through licking and grooming. Ingested chlorfenvinphos is vastly metabolized and rapidly excreted. In dogs treated orally with chlorfenvinphos ~86% and ~4% was eliminated in urine and feces respectively within 24 hours. In sheep tissues residues were low after topical administration.
Mechanism of action of chlorfenvinphos
As all organophosphates insecticides, chlorfenvinphos acts on the nervous system of the parasites (but also of mammals, birds, fish and many organisms!) as inhibitor of acetylcholinesterase (also known as AchE), an enzyme that hydrolyzes acetylcholine (Ach). Ach is a molecule involved in the transmission of nervous signals from nerves to muscles (so-called neuromuscular junctions) and between neurons in the brain (so-called cholinergic brain synapses).
AchE's role is to terminate the transmission of nervous signals where Ach is the neurotransmitter (there are several other neurotrasmitters). By inhibiting the activity of AchE, carbamates prevent the termination of those nervous signals, i.e. the neurons remain in constant activity and excitation, massively disturbing the normal movements of the parasites. The bottom line for the parasites is that they are paralyzed and die more or less quickly. Organophosphates bind irreversibly to AchE, in contrast with carbamates, another chemical class of parasiticides, which bind reversibly to AchE.
Click here to view the list of all technical summaries of antiparasitic active ingredients in this site.