FORMULATION: «transdermal solution» for topical administration (= pour-on, comparable to spot-ons)


CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED* (spectrum of activity):




  • Cats, 1.8 to 5.5 lbs bw: 1 unite applicator with 0.3 ml (containing 1.20 mg eprinomectin + 24.90 mg praziquantel)
  • Cats, 5.6 to 16.5 lbs bw: 1 uni applicator with 0.9 ml afoxolaner (containing 3.60 mg eprinomectin + 74.70 mg praziquantel)



  • LD50 (acute oral) in rats: estimate > 5000 mg/kg (according to SDS) for the spot-on.
  • Estimated Hazard Class according to the WHO: not applicable for veterinary medicines

Suspected poisoning? Read the articles on eprinomectin safety and praziquantel safety in this site.

WARNING !!!: Never use on cats products approved only for use on dogs, and vice-versa. Never use on cats or small dogs products approved for large dogs.

WARNING ! Heartworm preventatives stop development of microfilariae to adult worms but do not cure infections with adult worms. These preventative medicines are different from those curative anthelmintics that kill the adult worms. But preventatives may kill a few adult worms. If this happens, such dead worms may block lung vessels, which can be seriously harmful, even fatal for the pet. Consequently, heartworm preventatives are usually not administered to pets that are already infected with adult worms (hence the need for periodic diagnostic tests), because the risk of serious complications is real. The infection has first to be treated with adequate curative anthelmintics before preventative products are administered. This is however not trivial, and also risky for the same reason.

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


Risk of resistance development? YES

There are reports on resistance of Dirofilaria heartworms to macrocyclic lactones (e.g. eprinomectinivermectin, milbemycin oxime, moxidectin, selamectin, etc.) in the USA, reported particularly in the South. In this region, this means that if a heartworm preventative fails to achieve the expected efficacy, chance is real that it is due to resistance. Elsewhere and for the time being, if a heartworm preventative fails to achieve the expected efficacy, chance is very high that either the product was unsuited for the control of Dirofilaria heartworms, or it was used incorrectly. However, resistance cannot be excluded. And considering the massive use of macrocyclic lactones worldwide for heartworm prevention, it wouldn't be surprising that resistance emerges in other regions in the next years.

Alternatives to prevent heartworm resistance through product rotation: Currently there are no alternative active ingredients for rotation that ensure monthly heartworm prevention: all available products belong to the macrocyclic lactones that have the same mechanism of action.

There are no reports on resistance of cat tapeworms to praziquantel..

Learn more about resistance and how it develops.


Are the active ingredients of this product ORIGINAL* or 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: USA

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


CENTRAGARD is a once-a-month transdermal solution for heartworm prevention + roundworm and tapeworm control for cats.

Eprinomectin is a macrocyclic lactone introduced in the 1990s (by MERIAL). It has a systemic mode of action (through the blood). It is effective against roundworms (including heartworm microfilariae), but not at all against tapeworms, fleas or ticks (at the recommended dose). For decades it was used exclusively on cattle. Eprinomectin has a similar spectrum of activity as ivermectin.

Praziquantel is a veteran isoquinoline anthelmintic introduced in the 1970s (by BAYER). It has also a systemic mode of action. It is still the most effective and most vastly used parasiticide against tapeworms, both in pets and livestock, but has no efficacy against roundworms or external parasites. There are hundreds of antiparasitic brands for pets containing praziquantel, but rather few as a spot-on.

Topical products (mainly spot-ons and insecticide-impregnated collars) have some advantages over systemic products (mainly tablets for oral administration and injectables):

  • Most topical products kill or sterilize the external parasites before they bite and suck blood on the pet, whereas systemic products kill or sterilize the parasites only after their blood meal.
  • Topical products cannot be vomited.
  • Spot-ons and collars are very convenient to administer.

But topical products have also some disadvantages:

  • Non systemic topical products may not control parasites in some parts of the pet's body (e.g. the ears, below the tail, between the legs, etc.), whereas systemic products reach the blood-sucking parasites through the blood wherever they are.
  • Efficacy of topical products may be reduced or shortened through exposure to dirt, sun, shampooing, washing, rain, baths, etc., whereas efficacy of orally administered products is independent from these factors.

For an overview and a list of the most popular pet wormers click here.


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.