Tetramethrin is an antiparasitic active ingredient used in veterinary medicine in pets against external parasites (lice, mites, fleas, flies, ticks, etc.). It is also used against household pests. It belongs to the chemical class of the synthetic pyrethroids.
EFFICACY AGAINST PARASITES
Type of action: Broad spectrum contact, non systemic ectoparasiticide: insecticide, acaricide, tickicide, louisicide.
Main veterinary parasites controlled: flies, ticks, mites, lice, fleas, mosquitoes, etc.
Efficacy against a specific parasite depends on the delivery form and on the dose administered. 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.
Click here for general information on features and characteristics of PARASITICIDES.
Oral LD50, rat, acute*: 4640 mg/kg
Dermal LD50, rat, acute*: >5000 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.
Synthetic pyrethroids can be irritant for the skin and the eyes.
MRL (maximum residue limit) established for either beef, mutton pork or chicken meat*:
- CODEX: No
- EU: No
- USA: No
- AUS: No
* This information is an indicator of the acceptance of an active ingredient by the most influential regulatory bodies for use on livestock. An MRL for meat may be established also for agricultural pesticides that are not approved for use on animals but are used on commodities fed to animals. It may be also established 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.
General information on the safety of veterinary 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: SUMITOMO
Patent: Expired (particular formulations may be still patent-protected)
Use in LIVESTOCK: No
Use in HORSES: NO
Use in DOGS: Yes, scarce
Main delivery forms:
Use in human medicine: No
Use in public/domestic hygiene: Yes
Use in agriculture: Yes
Generics available: Yes
In pets: Yes, quite frequent worldwide in dog and cat fleas (Ctenocephalides spp).
Tetramethrin is a synthetic pyrethroid with a spectrum of activity similar to permethrin. It is scarcely used in pets and not at all in livestock. It is also used in agriculture as well as in public and domestic hygiene.
It is a rather old 2nd generation pyrethroid that breaks down quickly when exposed to sunlight.
Tetramethrin is a mixture of various optic isomers with different insecticidal efficacy. Commercial products may contain different isomer mixtures. For most users, it often doesn't make any difference regarding efficacy, because if one product uses a mixture with more of the most effective isomers, it will be used at a lower concentration than a product using a mixture with less effective isomers.
Efficacy of tetramethrin
Tetramethrin is an ectoparasiticide, i.e. active only against external parasites such as flies, lice, mosquitoes, ticks and mites. It can be considered as a broad-spectrum generalist, i.e. quite good against almost all insects, ticks and mites, but not outstanding against a particular parasite.
However, resistance to tetramethrin is widespread and can be very high in dog and cat fleas (Ctenocephalides spp). As a consequence, products with tetramethrin may not achieve the expected efficacy. The same applies to all other synthetic pyrethroids (e.g. cypermethrin, deltamethrin, flumethrin, etc.). And this is true for whatever delivery form: spot-on - squeeze-on - pipettes, shampoos, soaps, powders, etc.
Pharmacokinetics of tetramethrin
Topically administered tetramethrin remains mostly on the hair-coat of the treated animals and is very poorly absorbed through the skin (less than 2%).
Treated animals can ingest tetramethrin through licking or grooming. Absorption of ingested tetramethrin to blood is high. About 95% of the ingested amount is excreted within 5 to 7 days through feces and urine.
Mechanism of action of tetramethrin
Synthetic pyrethroids, including tetramethrin, have a similar mode of action as organochlorines. They act on the membrane of nerve cells blocking the closure of the ion gates of the sodium channel during re-polarization. This strongly disrupts the transmission of nervous impulses. At low concentrations insects suffer from hyperactivity. At high concentrations they are paralyzed and die.
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