Brand: MECWORMA ® & TAPE

Company: INTERNATIONAL ANIMAL HEALTH PRODUCTS


FORMULATION: «oral paste» in pre-charged syringes

ACTIVE INGREDIENT(S):

CHEMICAL CLASS of the active ingredient(s):


INDICATIONS

HORSES

PARASITES CONTROLLED* (spectrum of activity)

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


RECOMMENDED DOSE*

*Can be slightly different in some countries: read the product label!

  • ~200 mcg abamectin/kg bw, and ~9 mg/kg morantel tartrate/kg bw corresponding to 5.4 g of paste per 100 kg bodyweight.
  • The contents of one 32 g syringe are sufficient to treat one horse of 600 kg bodyweight. The plunger is calibrated in 100 kg increments which each deliiver 5.4 g oif paste.

SAFETY

  • LD50 (acute oral) in rats: ~2500 mg/kg (estimate calculated according to the WHO based on the abamectin LD50)
  • Estimated hazard class according to the WHO: not applicable for veterinary medicines

Suspected poisoning? Read the articles on abamectin safety and/or morantel safety in this site.

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

  • MEAT & OFFAL: AUS: DO NOT USE LESS THAN 28 DAYS BEFORE SLAUGHTER FOR HUMAN CONSUMPTION.
  • MILK: Do not use in animals producing milk for human consumption

WARNING !!!: Never use on humans, dogs or cats

You may be interested in the following articles in this site dealing with the general safety of veterinary products:


RESISTANCE PREVENTION

Risk of resistance? YES

  • Small strongyles (cyathostomes). Tolerance of small strongyles to macrocyclic lactones (e.g. abamectin, ivermectin, moxidectin), manifested as a low but significant worm egg output after treatment (determined after fecal egg counts) is not yet widespread, but has been already reported (e.g. in the UK, Germany, Italy, the USA, and Brazil). In Australia tolerance (expressed as faster recommencing of egg shedding) has been observed.  Cases of resistance to pyrantel (cross-resistance with morantel) have been also reported e.g. in Australia, Europe, the USA and Brazil).
  • Parascaris equorum: Resistance to macrocyclic lactones (e.g. ivermectin, moxidectin) has been reported (e.g. in the USA, UK and Australia). Cases of resistance to pyrantel (cross-resistance with morantel) have been reported (e.g. in the EU, USA and Canada).

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it may 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 oral pastes or gels.

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 product is marketed: Australia
GENERIC BRANDS available? YES

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


COMMENTS

This product is a classic oral paste for horses from INT. ANIMAL HEALTH PRODUCTS with abamectin and morantel generics.

Abamectin, a veteran endectocide introduced in the 1980s (by MSD AgVet → MERIAL) is considered as the "cheap" macrocyclic lactone. It is less potent and more toxic than ivermectin and other macrocyclic lactones but is often "good enough", with a similar spectrum of activity as ivermectin. Interestingly abamectin is widely used on livestock and horses in Australia and New Zealand but so far not in the EU, the USA and Canada. As for other macrocyclic lactones, abamectin has no efficacy whatsoever against tapeworms and flukes.

Morantel (in this case the tartrate salt) is a veteran anthelmintic introduced in the 1970s (by PFIZER → ZOETIS). It is a narrow-spectrum anthelmintic effective against roundworms in the gut, but not against those in other organs (skin, lungsm etc.). Nowadays it is rather scarcely used in horses or ruminants. Morantel has no residual effect, i.e. it kills the parasites after administration but does not protect against reinfestation.

Most macrocyclic lactones have about two weeks residual effect on horses because they are stored in body fat and progressively released. This, together with the time that worms need to develop inside the horse after infection (pre-patent period) allows to space the treatment intervals to 10 to 12 weeks in year-round control programs in many regions. For other active ingredients that have no residual effect such as fenbendazolemebendazole, or pyrantel the treatment interval is usually 4 to 6 weeks.

Whereas in ruminants abamectin administered at 200 mcg/kg controls a series of external parasites as well (mites, lice, etc.), such an indication is not approved in most countries in horses: external parasites have to be controlled with ectoparasiticides (e.g. pour-ons, sprays, etc.).

The logic oc combining two nematicides (i.e. roundworm killers) such as ivermectin and morantel is related to resistance management. Since both compounds have different mechanisms of action, it is assumed that resistance development will be prevented or at least delayed because the risk of simultaneous development of worm resistance to two different mechanisms of action is much smaller than to only one. However, this is only true if the concerned worms are still susceptible to both compounds. Otherwise, if the worms are already resistant to one of them, only one will work. It will initially do the job, but the risk of development of multiple resistance to both compounds is considerable. In addition, since morantel has no residual effect, a few days after administration only ivermectin will be active, meaning that the resistance-delaying effect of the combination gets lost: selection of ivermectin-resistant worms will continue undisturbed.

Many horse owners complain about the price of the oral pastes & gels for horses (with ivermectin or other macrocyclic lactones), compared with the much cheaper injectables for livestock with the same active ingredients, used at the same dose (200 mcg/kg). This is why off-label use of livestock ivermectin injectables in horses is very common worldwide, particularly in working horses of cattle and sheep ranches. The reason why injectables are mostly not approved for use on horses is apparently that, shortly after introduction, it was noticed that horses were more prone to develop severe clostridial infections at the injection site (due to contamination of the needles) and other undesired side effects than cattle or sheep. In addition, the pharmacokinetic behavior of ivermectin on horses is different than in ruminants. For these reasons oral pastes were developed for horses that do not show such side effects. However, in numerous countries (e.g. in Latin America) some ivermectin injectables for livestock are also approved for use on horses.

For an overview and a list of the most used oral paste & gel brands click here.


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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