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Brand: FIRSTMECTIN ® SE

Company: VIRBAC


FORMULATION: «drench» for oral administration.

ACTIVE INGREDIENT(S):

CHEMICAL CLASS of the active ingredient(s):


INDICATIONS: SHEEP

PARASITES CONTROLLED (spectrum of activity)


RECOMMENDED DOSE


SAFETY

  • LD50 (acute oral) in rats:
    • abamectin: a.i. 1.5 mg/kg (according to MSDS)
    • praziquantel: a.i. 2840 mg/kg (according to MSDS)
  • LD50 (acute dermal) in rats:
    • abamectin: a.i. >330 mg/kg (according to MSDS)
    • praziquantel: a.i. n.a.
  • Estimated hazard class according to the WHO: not applicable for veterinary medicines

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

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

  • Meat: Australia 14 days (ESI 28 days)
  • Milk for human consumption: DO NOT USE in dairy animals producing milk for human consumption or within 28 days prior to lambing.

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 of gastrointestinal roundworms to macrocyclic lactones (incl. abamectin): YES, resistance in ruminants is a very serious and increasing problem worldwide, particularly in sheep and goats. The most affected worm species are: Haemonchus spp, Ostertagia spp /Teladorsagia spp, Trichostrongylus spp, Nematodirus spp, Chabertia ovina.

Resistance of gastrointestinal roundworms to macrocyclic lactones (incl. abamectin) in sheep, goats and cattle has been reported almost worldwide, including the USA, UK, Australia and New Zealand. Based on the very abundant and frequent use of ivermectin and other macrocyclic lactones (with cross-resistance to ivermectin) in livestock it must be assumed that resistance of these roundworms to this chemical class will continue spreading and strengthening in the future.

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.

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.

There are so far no reports on resistance to sheep tapeworms to praziquantel.

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: Australia.
GENERIC BRANDS available? Yes a few ones, perhaps not with the same composition. This product itself contains generic abamectin and praziquantel.

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

For an overview on the most used antiparasitic pour-on brands click here.


COMMENTS

FIRSTMECTIN SE from VIRBAC is a combination of abamectin (mainly nematicide) and praziquantel (mainly cestodicide). There is another formulation from VIRBAC (FIRSTMECTIN) with the same composition but without Selenium.

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 in 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.

Praziquantel is a veteran anthelmintic introduced in the 1970s (by BAYER). It is highly effective against tapeworms (in horses mainly Anoplocephala spp) but has no efficacy whatsoever against roundworms. It is the anthelmintic most vastly used against tapeworms in horses and pets, used in hundreds of brands. Usage in livestock is rather scarce. Praziquantel has no residual effect, i.e. it kills the parasites after administration but does not protect against reinfestation.

The combination of abamectin and praziquantel makes sense because it extends the spectrum of activity of both active ingredients.

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.


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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