Brand: ACATAK ® DUOSTAR Pour-on


FORMULATION: «pour-on» for topical administration. To be applied in two 7cm wide bands, either side of the spine from shoulder to tail.


CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED (spectrum of activity)


  • 5 ml product / 50 kg bw, equivalent to 1.5 mg fluazuron/kg bw, + 0.5 mg ivermectin/kg bw
Body weight (kg) Total dose (mL)
For the prevention of body strike
101-150 15
151-200 20
201-250 25
251-300 30
301-350 35
351-400 40
401-450 45
451-500 50
501-550 55
551-600 60
601-650 65
>650 5 mL/50 kg

 Read the product label for further details on dosing and administration.


  • LD50 (acute oral) in rats:
    • fluazuron: 5000 mg/kg (source: MSDS)
    • ivermectin: ~ 50 mg/kg (source: MSDS)
  • LD50 (acute dermal) in rats:
    • fluazuron >2000 mg/kg (source: MSDS)
    • ivermectin: >600 mg/kg (source: MSDS)
  • Estimated hazard class according to the WHO: U: unlikely to present acute hazard

Withholding periods (=withdrawal times) for meat & milk

  • Meat: 42 days (ESI: 42 days). Calves that have suckled on treated cows must not be slaughtered less than 4 months since the last treatment of the cows.
  • Milk: not approved.

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

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


Risk of resistance in cattle ticks: YES, so far rather low to moderate.

Resistance of cattle ticks to fluazuron was reported first in 2010 in two properties in Queensland. In laboratory tests on engorged adult ticks of these properties the concentration of fluazuron required for inhibiting larval hatching out of the laid eggs was 20x higher than for susceptible ticks (Resistance Ratio =20). However, to our knowledge no subsequent confirmation or otherwise characterization of these resistant ticks (incidence, prevalence, mechanism, etc.) has been published so far.

In 2014 another publication reported the first case of low-level fluazuron-resistant cattle ticks in one property in Brazil. These ticks (Jaguar strain) were found to be simultaneously resistant to six chemical classes: besides benzoylphenyl ureas (fluazuron) they showed different degrees of resistance to organophosphates (chlorpyrifos), synthetic pyrethroids (cypermethrin), amidines (amitraz), phenylpyrazoles (fipronil) and macrocyclic lactones (ivermectin). This case confirms that cattle ticks can become simultaneously resistant to both fluazuron and macrocyclic lactones.

Although the situation is not yet dramatic, these cases are a warning. Considering the very strong and increasing reliance on fluazuron and macrocyclic lactones (doramectin, ivermectin, moxidectin, etc.) for cattle tick control in many regions, development and spreading of resistance to these two chemical classes is only a matter of time, unless serious measures are taken to prevent it.

Theoretically, the simultaneous use of fluazuron and ivermectin against cattle ticks should contribute to prevent or at least delay the development of resistance because both compounds control ticks through a different mechanism of action, which is generally considered as a method to delay resistance. It remains open whether the simultaneous use of both compounds is  better or not than the alternate use (rotation) in order to delay resistance. Time will show.

Alternative chemical classes/active ingredients to prevent fluazuron-resistance of cattle ticks through product rotation:

Risk of resistance in gastrointestinal roundworms? YES, high in cattle particularly in for Cooperia spp & Ostertagia spp

Resistance of gastrointestinal roundworms to ivermectin 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 everywhere, or may not be available as pour-ons.

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.

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 (maybe under another TM): Australia
GENERIC BRANDS available? NO, so far, in this particular composition.

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

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


ACATAK DUOSTAR Pour-on for Cattle is a logic further development of ACATAK, the first and original brand containing fluazuron introduced by CIBA-GEIGY (later NOVARTIS) in 1994. ACATAK was the first and remains the only tick development inhibitor for use on cattle worldwide. It is logic because it combines the long protection of cattle against cattle ticks provided by fluazuron with the broad-spectrum parasiticidal efficacy of ivermectin.

It is the most successfull parasiticide ever developed, nowadays used in thousands of brands for pets, livestock and also in agriculture.

Ivermectin was the first macrocyclic lactone introduced in the market in the early 1980s (by MSD Agvet, later MERIAL). It was a milestone and a tremendous progress that revolutionized the control of veterinary parasites. It is a broad-spectrum systemic parasiticide effective against numerous parasites, both internal (mainly roundworms) and external (mainly lice, mites, buffalo flies, etc.). It is the most successfull parasiticide ever developed, nowadays used in thousands of brands for pets, livestock and also in agriculture.

Fluazuron has also a systemic mode of action and it reaches the ticks through the blood of the host. After topical administration, the active ingredient reaches the bloodstream of the host either through the skin (transdermally) or through ingestion (mainly through licking). Being very lipophilic, it is deposited in the body fat of cattle for weeks, from where it is slowly released back to the blood and is excreted. Ticks (adults, larvae and nymphs) that feed blood on cattle ingest fluazuron with their blood meal. As a consequence eggs laid by female ticks won't hatch, and larvae and nymphs will die when they attemp molting. Fluazuron has no efficacy whatsoever on worms or other external parasites of cattle.

Being a tick development inhibitor fluazuron does not kill the ticks immediately, i.e. it has no knockdown effect. But the combination with ivermectin adds knock-down efficacy against cattle ticks. This means that ACTAK DUOSTAR can be also used to treat established infestations, although best results will be obtained after strategic use i.e. treating all cattle in a property before the onset of the tick season, usually in early to mid spring, and to re-treat them at the recommended interval, usually when first ticks are seen again on cattle. These effect results in a strong population control in the property, provided all cattle are treated. If only part of the cattle are treated, the effect on the tick population will be weaker. Used this way 3 and sometimes only 2 treatments may be sufficient to protect cattle against cattle ticks during the whole tick season.

Fluazuron is partially excreted through the milk in lactating cows. As a consequence calves sucking milk from treated mother cows get enough fluazuron to be protected against ticks for weeks: they don't need to be treated. However protection of lactating mother cows is shorter than in non-lactating animals, because the administered dose is excreted faster in these cows than in non-lactating cattle.

The very long protection of cattle against re-infestations with cattle ticks is achieved by fluazuron, not by ivermectin. The concentration of ivermectin in the blood of treated cattle drops below the effective concentration a few days after treatment. Used at the recommended dose, the length of protection of cattle against re-infestation (i.e the residual effect) with cattle ticks provided by fluazuron depends mainly on three major factors: breed, lactation and tick pressure. Protection on non-lactating pure Zebu cattle breeds (Bos indicus) can easily last more than 12 weeks. Protection on non-lactating European breeds (Bos taurus) is usually around 10 weeks. Protection on crossbred cattle is somewhere in between. The difference is explained by the natural resistance of Zebu cattle to ticks. It is known that survival of cattle ticks on Zebu cattle is about 15 times lower than on European breeds.

Protection on lactating cows may be 4 to 6 weeks shorter than in non-lactating cows, depending also on milk production. The higher the amount of milk produced, the shorter the protection.

The effect of tick pressure affects both efficacy as well as length of protection. No product, including ACATAK DUOSTAR achieves 100% tick control. Therefore the more ticks infest a property (=tick pressure), the more ticks will infest cattle grazing there.

Tick control on cattle is a complex business. To ensure best use of this and other products against the cattle tick Rhipicephalus (Boophilus) microplus we strongly recommend you to read the specific article about these ticks in this site (click here).

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