Brand: PANACUR ® SC 2.5%

Company: MERCK (=MSD) ANIMAL HEALTH


DELIVERY FORM: «drench» for oral administration.

ACTIVE INGREDIENT(S): fenbendazole 25 mg/mL (equivalent to 2.5%). This formulation contains also 0.4 mg/mL elemental selenium and 0.94 mg/mL elemental cobalt.

CHEMICAL CLASS of the active ingredient(s): benzimidazole


INDICATIONS: SHEEP


PARASITES CONTROLLED* (spectrum of activity)

* Country-specific differences may apply: read the product label.

Sheep


RECOMMENDED DOSE*

* Country-specific differences may apply: read the product label.

  • Sheep: 1 mL product/5 kg bw (equivalent to 5.0 mg of fenbendazole/kg)

SAFETY

  • LD50 (acute oral) in rats: >10000 mg/kg (for the a.i. according to MSDS)
  • LD50 (acute dermal) in rats: n.a.

Suspected poisoning? Read the article on fenbendazole safety in this site.

Withholding periods (=withdrawal times) in days for meat & milk (country-specific differences may apply: read the product label)

  • Meat: UK 15 days.
  • Milk for human consumption: UK 7 days

RESISTANCE PREVENTION

Risk of resistance? YES, resistance of gastrointestinal roundworms to all benzimidazoles (incl. fenbendazole) in ruminants is a very serious and increasing problem worldwide, particularly in sheep and goats, but also in cattle. The most affected worm species are:

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it can be due to resistance and not to incorrect use, which is usually the most frequent cause of product failure.

Alternative chemical classes/active ingredients to prevent resistance of gastrointestinal roundworms through product rotation:

These alternative products may not be available in all countries, or may not be available as drenches, or may not be effective against all the concerned parasites.

There are only very few reports on resistance of Moniezia spp tapeworms to benzimidazoles (not in Europe) but it is certainly not a widespread problem so far.

It is highly recommended to periodically check the resistance status of each property performing appropriate tests (e.g. fecal egg counts) under supervision of a veterinary doctor. Such tests are now routinely available for most producers in developed countries.

Learn more about resistance and how it develops.


MARKETING

Are the active ingredients of this product ORIGINAL* or GENERICS**?

  • GENERICS

*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.

COUNTRIES where this brand/product is marketed: UK and other EU countries.
GENERIC BRANDS available? Yes, in most countries

Click here to learn more about GENERIC vs. ORIGINAL drugs.

For an overview on the most used drench brands for livestock click here.


COMMENTS

PANACUR is the original brand for products containing fenbendazole introduced already in the 1970s by HOECHST (later acquired by INTERVET, now MERCK MSD ANIMAL HEALTH = MSD ANIMAL HEALTH).

All benzimidazoles are veteran anthelmintics. Fenbendazole has a broad-spectrum of activity against roundworms (gastrointestinal and pulmonary) & tapeworms, but is ineffective against flukes. Fenbendazole also kills eggs of roundworms (ovicidal activity). As all benzimidazolesfenbendazole has no efficacy whatsoever against external parasites (ticksflies, lice, mites, etc). Among the benzimidazoles fenbendazole is quite comparable with oxfendazole in terms of efficacy and safety.

As all benzimidazoles (as well as other anthelmintics such as levamisole, monepantel, and tetrahydropyrimidines), fenbendazole administered as a drench has no residual effect, i.e. it kills the parasites shortly after administration, but does not significantly protect the animals against re-infestation by infective stages in their environment.

Fenbendazole is abundantly used worldwide in numberless generic brands for livestock, horses and pets.

Drench is the preferred delivery form for use on cattle, sheep and goats, but in many countries it is also available in the form of feed additives (mainly for pig & poultry) and other delivery forms for oral administration (boluses, tablets, pastes, etc). As most benzimidazoles it is not appropriate for intramuscular or subcutaneous injection due to its poor solubility in water, but intraruminal injection is very popular in Latin America.

Both for livestock and pets fenbendazole is often used in combinations that broaden the spectrum of activity or try to overcome potential resistance. Typical mixtures for livestock include a flukicide (e.g. closantel, etc.) and/or a macrocyclic lactone, and/or levamisole, although such mixtures are not approved everywhere. For dogs and cats it is often combined with a taenicide (e.g. praziquantel).

Unfortunately, resistance of several gastrointestinal roundworms to all benzimidazoles (including fenbendazole) is already very high and very frequent worldwide in sheep and goats, slightly lower in cattle, which has significantly reduced their usage in livestock. Nowadays more convenient pour-ons and injectables containing macrocyclic lactones (e.g. abamectin, doramectin, eprinomectin, ivermectin, moxidectin) are often preferred over drenches with benzimidazoles. Macrocyclic lactones also ensure several weeks protection against re-infestation by several worm species, in contrast with all benzimidazoles that lack any residual effect.

In ruminants, reducing the amount of feed slows down the exit flow of the rumen and prolongs the time during which the active ingredient remains there and is absorbed. Consequently it is advisable to reduce the access of animals to feed (especially to fresh pasture, not to water) 24 hours before administration. For the same reason, it is better to keep the animals away from food for about 6 hours after drenching. However sick or weak animals should not be kept away from food and fasting animals should have access to water. In cattle, a fiber-rich diet also increases the bioavailability of fenbendazole.

Fenbendazole active ingredient is a solid compound poorly soluble in water and in drenches it is formulated as a suspension (not as a solution or as an emulsion). A key unfavorable feature of all suspensions is that the suspended solid particles tend to fall down to the bottom of the container and sediment, very much like sand in water. This means that suspensions must be thoroughly shaken before use. How fast the suspension sediments and how easily shaking the container redistributes the suspension depends on the formulation quality. A good formulation sediments slowly and shaking will re-suspend it quickly. Bad formulations sediment quickly and shaking re-suspends them slowly.

Thoroughly shaking suspensions before use is crucial for efficacy. If the active ingredient remains in the sediment, a few animals may get most of the active ingredient and will be overdosed, and the large majority will get almost only solvents and will be underdosed.


DISCLAIMER

This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics. 

Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.

In case of doubt contact the manufacturer or a veterinary professional.

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