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Common name:  MEBENDAZOLE

Type: veterinary medecine
Chemical class: benzimidazole

CHEMICAL STRUCTURE

Molecular structure of MEBENDAZOLE 

 


EFFICACY AGAINST PARASITES

Type of action: broad-spectrum nematicide and taenicide anthelmintic, endoparasiticide
Main veterinary parasites controlled: gastrointestinal and respiratory roundworms (= nematodes) and tapeworms

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.


DOSING

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.

The table below indicates some usual dosing recommendations for mebendazole issued by manufacturers or documented in the scientific literature. They may not be approved in some countries.

Mebendazole is a broad spectrum anthelmintic effective against roundworms and, depending on the dose also against some tapeworms (e.g. Moniezia spp) as welll. It is ineffectice against flukes (e.g. Fasciola hepatica adults) at the usual therapeutic dose. It is completele inefective against external parasites. Oral administration is the rule. It is used scarcely in livestock (manily in drenches and feed additives), more in pets (often in tablets, pills, etc. or oral suspensions) and horses (mostly in oral pastes & gels). There are numerous generic brands worldwide, also in mixtures with other anthelmintics.

In ruminants, a 50% reduction of the diet 36 prior and 8 hours after treatment slows down the passage through the stomach, which increases the bioavailability of benzimidazoles and their metabolites and consequently its efficacy against gastrointestinal parasites.

In carnivores (incl. dogs and cats) delivery with the food increases the bioavailability of all benzimidazoles resulting in a better efficacy.

All benzimidazoles have almost no residual effect, i.e. they kill the parasites during a few hours after treatment but offer no significant protection against re-infestation.

Dosing recommendations for MEBENDAZOLE
DOGS
Delivery Parasites Dose (against mebendazole-susceptible parasites)
Oral Ascarids (Toxocara, Toxascaris)
20-22 mg/kg/day x3 days; or 10 mg/kg 2x/day, 2 consecutive days
Oral Ancylostoma caninum, Uncinaria stenocephala
22 mg/kg/day x3 days; or 10 mg/kg 2x/day, 5 consecutive days
Oral Angiostrongylus vasorum 22 mg/kg/day x3 days; or 10 mg/kg 2x/day, 5 consecutive days
Oral Capillaria aerophila 6 mg/kg 2x/day, 5 consecutive days
Oral Taenia spp 22 mg/kg/day x3-5 days; or 10 mg/kg 2x/day, 5 consecutive days
Oral  Trichuris vulpis <2 kg bw: 50 mg/kg 2x/day; >2 kg bw: 100 mg/kg 2x/day
CATS
Delivery Parasites Dose (against mebendazole-susceptible parasites)
Oral Ascarids (Toxocara, Toxascaris)
10 mg/kg 2x/day, 2 consecutive days
Oral Ancylostoma, Uncinaria 10 mg/kg 2x/day, 5 consecutive days
Oral Taenia spp 10 mg/kg 2x/day, 5 consecutive days
CATTLE
Delivery Parasites Dose (against mebendazole-susceptible parasites)
Oral Roundworms 15 mg/kg
Oral Dictyocaulus viviparus 20 mg/kg
Oral Moniezia spp 10 mg/kg
SHEEP  
Delivery Parasites  Dose (against mebendazole-susceptible parasites)
Oral Gastrointestinal roundworms 15-20 mg/kg
Oral Cysts of Echinococcus granulosus 50 mg/kg/day during 3 months
Oral Cysts of Taenia hydatigena 50 mg/kg/day during 3 months
Oral Muellerius capillaris, Protostrongylus rufescens 15 mg/kg on 3 consecutive days
SWINE 
Delivery Parasites  Dose (against mebendazole-susceptible parasites)
Oral Ascaris suum 30 mg/kg in the feed during 5 days
Oral Ascaris suum migrating larvae 30 mg/kg in the feed during 10 days
Oral Strongylids 30 mg/kg in the feed during 5 days
Oral Trichuris spp 30 mg/kg in the feed during 5 days
HORSES
Delivery Parasites  Dose (against mebendazole-susceptible parasites)
Oral Gastrointestinal roundworms 5-10 mg/kg
Oral Dictyocaulus arnfieldi 20 mg/kg x5 consecutive days
Oral Anaplocephala spp 20 mg/kg
POULTRY
Delivery Parasites Dose (against mebendazole-susceptible parasites)
Oral Gastrointestinal roundworms 60 ppm (= mg/kg) in feed x7 days (partridges & pheasants 120 ppm)
Oral Tapeworms 120 ppm (= mg/kg) in feed x10 días

DISCLAIMER: Liability is denied for any possible damage or harm to persons, animals or any other goods that could follow the transmission or use of the information, data or recommendations in this site by any site visitor or third parties.


SAFETY

Oral LD50, rat, acute*: 714-1434 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: Yes

* 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.

Learn more about mebendazole safety (poisoning, intoxication, overdose, antidote, symptoms, etc.).

General information on the safety of veterinary antiparasitics is available in specific articles in this site (click to visit):

WARNING

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: JANSSEN
Some original brands: OVITELMIN, SUPAVERM
Patent: Expired (particular formulations may be still patent-protected)

Use on LIVESTOCK: Yes, scarce
Use on HORSES: Yes, moderate
Use on DOGS and CATS: Yes, moderate


Main delivery forms: 

Use in human medicine: Yes
Use in public/domestic hygiene: No
Use in agriculture: No
Generics available:  Yes


PARASITE RESISTANCE

On livestock & horses: Yes, as all benzimidazoles, very frequent worldwide in gastrointestinal roundworms in sheep, goats and cattle.
On dogs and cats: No

Learn more about parasite resistance and how it develops.


SPECIFIC FEATURES

Mebendazole is a veteran anthelmintic (wormer) compound belonging to the chemical class of the benzimidazoles. Mebendazole is moderately used on pigs, dogs ans cats. It is very scarcely used in ruminants. It is vastly used on horses.

For livestock it is available in the form of drenches, feed additives, bolus, tablets, pills, etc, all for oral administration, mostly in feed-additives for pigs. There are no classic injectables or pour-ons with mebendazole.

For horses it is available mainly in the form of feed additives and oral pastes.

For dogs and pets it is usually available in the form of drenches and tablets, pills, etc.

For pets it is very often used in combinations that broaden the spectrum of activity, mostly a taenicide (e.g. praziquantel).

Mebendazole was the first benzimidazole approved for use on humans.

Efficacy of mebendazole

Mebendazole has a broad-spectrum of activity against gastrointestinal roundworms and lungworms of livestock, including adults and L4-larvae of the most important species (e.g. of the genus Bunostomum, Haemonchus, Ostertagia - Teladorsagia, Trichostrongylus, Cooperia, Nematodirus, Chabertia, Oesophagostomum, Trichuris, Dictyocaulus, Muellerius, etc.) as well as arrested larvae of several species. It is also effective against most livestock tapeworms (e.g. Moniezia, Taenia).

In horses it controls the major parasitic roundworms such as Large Strongyles (Cyathostomins), Small Strongyles (Strongylus spp), Parascaris equorum, etc. as well as tapeworms. (e.g. Anaplocephala spp).

It is also effective against the major parasitic roundworms (e.g. Ancylostoma, Toxocara, Trichuris, Uncinaria) and tapeworms (e.g. Echinococcus, Dipylidium, Taenia, etc.) of dogs and cats.

Mebendazole 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.

Mebendazole 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.

At the therapeutic dose mebendazole is not effective against flukes and whatsoever external parasites.

Resistance of worms to benzimidazoles, including mebendazole in dogs, cats, pig and poultry is not a problem so far. However resistance of several gastrointestinal roundworms to all benzimidazoles, including mebendazole 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 mebendazole

Mebendazole is very poorly soluble in water. Orally administered mebendazole is poorly absorbed into the bloodstream: ~30% in pigs, and <10% in dogs. This means that significant amounts remain in the gastrointestinal tract and are available for the control of gut dwelling roundworms and tapeworms.

Absorbed mebendazole is quickly broken down in the liver to metabolites without anthelmintic efficacy. Both the parent molecule and its metabolites are excreted mainly through bile and feces, the rest through urine. However, there are important species-specific differences. Whereas in dogs >90% od the administered dose is excreted through feces, up to 50% is excreted through urine in swine.

Influence of parasites. Heavy liver fluke infestations in sheep slow down the metabolism of mebendazole in the liver, which increases its bioavailability and prolongs the residence time. This may require longer withholding periods.

Mechanism of action of mebendazole

The molecular mode of action of all benzimidazoles, including mebendazole, 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.

Click here to view the list of all technical summaries of antiparasitic active ingredients in this site.

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