Brand: DUOTECH ® Oral Suspension


FORMULATION: «drench» for oral administration.


CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED (spectrum of activity)


Sheep: 1 ml product/5 kg bw, equivalent to 10 mg/kg closantel, and 5 mg/kg oxfendazole.

  • ≤7.5 kg: 1 ml product
  • 7.5-15 kg: 2 ml product
  • 16-20 kg: 4 ml product
  • 21-25 kg: 5 ml product
  • 26-30 kg: 6 ml product
  • 31-40 kg: 8 ml product
  • 41-50 kg: 10 ml product
  • 51-60 kg: 12 ml product
  • 61-70 kg: 14 ml product
  • 71-80 kg: 16 ml product

Read the product label for further details on dosing.


  • LD50 (acute oral) in rats:
    • closantel: a.i. 262 to 342 mg/kg (depending on the studies)
    • oxfendazole: a.i. >6400 mg/kg
  • LD50 (acute dermal) in rats: n.a.

Suspected poisoning? Read the articles on closantel safety and oxfendazole safety in this site.

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

  • Meat: Ireland: 18 days;
  • Milk: Ireland: Not authorised for use in ewes producing milk for human consumption including during the dry period. Do not use within 1 year prior to the first lambing in ewes 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.

Resistance of gastrointestinal roundworms to all benzimidazoles (incl. oxfendazole) 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: Haemonchus spp, Ostertagia spp /Teladorsagia spp, Trichostrongylus spp, Nematodirus spp and Chabertia ovina.

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

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 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.

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.

There are only very few reports on resistance of Moniezia spp tapeworms to benzimidazoles (e.g. fenbendazole) but it is certainly not yet a widespread problem.

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 & other EU countries
GENERIC BRANDS available? Yes, but not a lot in most countries in this particular combination, if at all.

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

For an overview on the most used antiparasitic drenches click here.


DUOTECH is a classic anthelmintic drench for sheep with generic closantel and oxfendazole from NORBROOK. Closantel is effective mainly against liver flukes and a few roundworm species, and oxfendazole is effective against most gastrointestinal roundworms and tapeworms

Closantel is a veteran flukicide (introduced in the 1970s by JANSSEN) but a rather particular one, because it is effectiev against liver flukes, against a few roundworms and against a few external parasites as well (e.g. nasal bots). 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 (>5 weeks ~90%; 3-4 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.

Oxfendazole is a veteran broad-spectrum benzimidazole (introduced in the 1970s by WELLCOME, SYNTEX). It is effective against roundworms (gastrointestinal and pulmonary) & tapeworms, but is ineffective against flukesOxfendazole also kills eggs of roundworms (ovicidal activity). As all benzimidazolesoxfendazole has no efficacy whatsoever against external parasites (ticksflies, lice, mites, etc). Among the benzimidazoles oxfendazole is quite comparable with fenbendazole in terms of efficacy and safety.

As all benzimidazoles (as well as other anthelmintics such as levamisole, monepantel, and tetrahydropyrimidines), oxfendazole 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.

Unfortunately, resistance of several gastrointestinal roundworms to all benzimidazoles (including oxfendazole) is already very high and very frequent worldwide in sheep and goats, slightly lower in cattle, which has significantly reduced their usage in livestock. The presence of closantel in this product should ensure efficacy against benzimidazole-resistant Haemonchus contortus, but not against other resistant worms that do not feed blood.

Nowadays more convenient pour-ons and injectables containing macrocyclic lactones (e.g. abamectin, doramectin, eprinomectin, ivermectin, moxidectin) are often preferred over drenches with benzimidazoles or combinations. 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.

As most benzimidazoles, oxfendazole active ingredient is  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.

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.