Brand: FLUKIVER ® 50 mg/mL Solution for Injection

Company: ELANCO

FORMULATION: «injectable» solution to be administered subcutaneously.

ACTIVE INGREDIENT(S): closantel: 50 mg/mL (=5%)

CHEMICAL CLASS of the active ingredient(s): salicylanilide


PARASITES CONTROLLED (spectrum of activity)


 1 ml product/20 kg bw, equivalent to 2.5 mg closantel/kg bw. Against adults of Fasciola hepatica, Fasciola gigantica, Haemonchus placei (also immatures), Bunostomum phlebotomum and Oesophagostomum radiatum.

 1 ml product/10 kg bw, equivalent to 5 mg closantel/kg bw. Against adults and immatures of Fasciola hepatica, (only >6 weeks larvae; aver. efficacy against 6 weeks larvae 73%), Fasciola gigantica (only >8 weeks larvae), Haemonchus placei (also immatures), Bunostomum phlebotomum and Oesophagostomum radiatum and Hypoderma spp.

Residual activity = protection period:


  • LD50 (acute oral) in rats: for closantel a.i. 262 to 342 mg/kg (depending on the studies)
  • LD50 (acute dermal) in rats: n.a.

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

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

  • Meat: Ireland 77 days
  • Milk for human consumption: Not authorised for use in cattle producing milk for human consumption including during the dry period. Do not use during the last trimester of pregnancy in heifers which are intended to produce 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:


Risk of resistance: YES. Cases of resistance to closantel have been reported for Haemonchus contortus and Fasciola hepatica, but seems not to be widespread in most countries.

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it cannot be excluded that this 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 liver flukes through product rotation:

  • Clorsulon: effective only against ≥8 weeks old liver flukes.
  • Nitroxinil: effective only against ≥8 (sheep) or ≥7 (cattle) weeks old liver flukes.
  • Oxyclozanide (salicylanilide): effective only against ≥12 (sheep) or ≥10 (cattle) weeks old liver flukes.
  • Rafoxanide (salicylanilide): effective only against ≥6 weeks old liver flukes.
  • Triclabendazole (benzimidazole): effective against adult liver flukes and all immature stages. However, resistance has been reported in various countries worldwide and is increasing.

These alternative products may not be available in all countries or may not be available as injectables.

There are also a few reports on liver fluke populations in sheep resistant to rafoxanide and closantel (both salicylanilides), probably with cross-resistance to nitroxinil, and also to clorsulon. So far resistance to these compounds seems to be less frequent than to resistance to benzimidazoles.

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 brand/product is marketed: Ireland and other EU countries
GENERIC BRANDS available? Yes, but rather few in many EU countries, if at all.

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

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


FLUKIVER is the original closantel brand developed by JANSSEN in the 1970s, now owned by ELANCO.

Closantel is a narrow spectrum but rather particular anthelmintic, because it is effective against some internal parasites (e.g. Haemonchus contortus and Fasciola hepatica) and a few external parasites as well (e.g. cattle grubs). It has also an effect on the viability of some tick species, but this is usually of no practical use under most field conditions in open systems: numerous alternative hosts allow survival of enough ticks that ensure the infestation of the environment.

Closantel offers good control of adult liver flukes, but efficacy against immatures is incomplete (6 weeks ~73%): this is important because immature stages are the most damaging ones.

Efficacy against roundworms is usually limited to blood-feeding species. This is related to the fact that ingested closantel is quickly absorbed to blood where it binds strongly to plasma proteins. There it remains for several days before being excreted. In contrast, its concentration in the tissues is usually too low to kill worms that do not feed blood, which are the majority among the roundworms that infect sheep.

Click here for general information on good practices for the prevention and control of gastrointestinal worms in livestock.


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.