EFFICACY AGAINST PARASITES
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*: >10000 mg/kg
Dermal LD50, rat, acute*: not found
* 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) established for either beef, mutton pork or chicken meat*:
- CODEX: No
- EU: Yes
- 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.
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 products for livestock on dogs and cats unless they are explicitly approved for both livestock and pets. Pets may not tolerate livestock formulations
It is obvious that veterinary products are not intended for and should never be used on humans!!!
MARKETING & USAGE
Decade of introduction: 1970
Introduced by: SMITH KLINE → PFIZER → ZOETIS
Some original brands: NEPLON, LODITAC
Patent: Expired (particular formulations may be still patent-protected)
Use on LIVESTOCK: Yes, scarce, mainly in pig and poultry
Use on HORSES: Yes, scarce
Use on DOGS and CATS: Yes, very scarce
Main delivery forms:
Use in human medicine: No
Use in public/domestic hygiene: No
Use in agriculture: No
Generics available: Yes
Oxibendazole is a veteran anthelmintic (wormer) compound belonging to the chemical class of the benzimidazoles. Oxibendazole is used on pig and horses, and only marginally on ruminants, dogs and cats.
For livestock oxibendazole is available mainly in the form of feed additives, but there are also a few drenches, bolus, tablets, pills, etc, all for oral administration, mostly alone. There are no classic injectables or pour-ons with oxibendazole. It was used on ruminants in the past but has been replaced by more effective active ingredients.
For pets it is also used in mixtures that broaden the spectrum of activity, mostly with a taenicide (e.g. praziquantel).
Efficacy of oxibendazole
Oxibendazole has a broad-spectrum of activity against gastrointestinal roundworms and lungworms of pig, including adults and larvae of the most important species (e.g. of the genus Ascaris, Hyostrongylus, Metastrongylus, Oesophagostomum, Strongyloides, Trichuris, etc.).(e.g. of the genus Ascaris, Hyostrongylus, Metastrongylus, Strongyloides, Oesophagostomum, Trichuris, etc.).
Oxibendazole is absorbed slowly in the stomach. Therefore the longer it remains there, the better the efficacy. In carnivores (e.g. dogs and cats) and other animals with a simple stomach the passage through the stomach is rather fast and therefore a higher dosage or repeated treatments are usually required.
Oxibendazole has no residual effect. This means that a single administration will kill the parasites present in the host at the time of treatment, but it will not protect against re-infestations.
Resistance of worms to benzimidazoles, including oxibendazole in dogs, cats, pig and poultry is not a problem so far. However resistance of several gastrointestinal roundworms to all benzimidazoles, including oxibendazole is already very high and very frequent worldwide in sheep and goats, slightly lower in cattle. For this reason, the risk that benzimidazoles fail to protect ruminants against gastrointestinal roundworms is considerable worldwide.
Pharmacokinetics of oxibendazole
As most benzimidazoles, oxibendazole is almost insoluble in water and orally administered is poorly absorbed into the bloodstream. This means that significant amounts remain in the gastrointestinal tract and are available for the control of gut-dwelling roundworms and tapeworms. But blood levels are low and efficacy against tissue-dwelling worms may be lower or insufficient.
Little information is available on the metabolism of oxibendazole. Following oral administration to sheep maximum plasma levels were recorded after 6 hours, and 24 hours later ~35% of the administered dose was already excreted through urine. Absorbed oxibendazole is broken down in the liver to metabolites without anthelmintic activity.
Mechanism of action of oxibendazole
The molecular mode of action of all benzimidazoles, including oxibendazole, consists in binding to tubulin, a structural protein of microtubules. These microtubules are important organelles involved in the motility, the division and the secretion processes of cells in all living organisms. In the worms the blocking of microtubules perturbs the uptake of glucose, which eventually empties the glycogen reserves. This blocks the whole energy management mechanism of the worms that are paralyzed and die or are expelled.
Since cell division is also disturbed, worm egg production and development is also blocked by benzimidazoles, i.e. most of them also have an ovicidal effect.