Brand: ZOLVIX ® Broad Spectrum Oral Solution


DELIVERY FORM: «drench» for oral administration.

ACTIVE INGREDIENT(S): monepantel: 25 mg/mL (equivalent to 2.5%). 

CHEMICAL CLASS of the active ingredient(s): amino-acetonitrile derivative


PARASITES CONTROLLED* (spectrum of activity)

* Country-specific differences may apply: read the product label.



* Country-specific differences may apply: read the product label.

  • Sheep2.5 mg monepantel/kg bw equivalent to 1 mL product /10 kg bw
Sheep weight (kg) Dose rate (mL)
10 - 25 1.5
16 - 20 2
21 - 25 2.5
26 - 30 3
31 - 35 4.5
36 - 40 4
41 - 50 5
51 - 60 6
61 - 70 7
> 70 1 ml for add. 10 kg


  • LD50 (acute oral) in rats: >2000 mg/kg (derived from a.i. according to MSDS)
  • LD50 (acute dermal) in rats: >2000 mg/kg (derived from a.i. according to MSDS)

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

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

  • Meat:
    • UK: 7 days
    • Australia: 14 days (ESI 115 days)
    • NZL: 7 days
  • Milk for human consumption:
    • UK & Australia: DO NOT USE in female sheep which are producing, or may in the future produce milk or milk products for human consumption.
    • NZL: 35 days

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

Monepantel is effective against gastrointestinal roundworms resistant to all other classes of usual anthelmintics used in sheep (mainly benzimidazoles, levamisole, morantelmacrocyclic lactones and salicylanilides). If it has never been used before in a property, there is almost ni risk that it initially fails due to resistance, since it has no cross-resistance with other anthelmintics. However, resistance of Teladorsagia circumcincta and Trichostrongylus colubriformis to monepantel were reported in goats and sheep in one farm in New Zealand, after only 2 years of uninterrupted use of the product. In 2016 a first case of Haemonchus spp resistance was confirmed in a sheep property in NSW, Australia. In 2018 a case of resistence of Trichostrongylus vitrinus in sheep has been reported in the UK. These are clear warnings, and confirm that the risk that gastrointestinal roundworms develop resistance to any anthelmintic is very high in case of uninterrupted use.

This means that if this product does not achieve the expected efficacy against the mentioned parasites after it has been used for the first time, it is most likely due to incorrect use, not to resistance. But if the product has been used uninterruptedly for years, the risk is real that product failure is due to resistance development.

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, or may not be effective against all the concerned parasites.

It is highly recommended to periodically check the resistance status of each property performing appropriate tests (e.g. fecal egg counts) under supervision of a veterinary doctor. Such tests are now routinely available for most producers in developed countries.

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: UK + EU, Australia, New Zealand, Argentina, Uruguay, etc.

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

For an overview on the most used drench brands for livestock click here.


ZOLVIX is the original brand containing monepantel introduced by Novartis in 2005.

After the launch of ivermectin in 1980 (as the first among several macrocyclic lactones) it took 25 years until monepantel became available, an anthelmintic compound with a new mechanism of action against gastrointestinal roundworms of sheep. Unfortunately it must be expected that the introduction of a next class of anthelmintics with a new mechanism of action may take another 25 years, or longer.

Monepantel is highly effective against the most damaging gastrointestinal roundworms of sheep (Haemonchus spp, Teladorsagia sppTrichostrongylus spp, Nematodirus spp, Cooperia spp Oesophagostomum venulosumChabertia ovina). However, at the therapeutic dose it is not effective against other important gastrointestinal worms such as Bunostomum spp, Strongyloides spp, and Trichuris ovis.

At the therapeutic dose monepantel is not effective against non-gastrointestinal worms such as lungworms (e.g. Dictyocaulus spp) or eyeworms (e.g. Thelazia spp), nor against tapeworms or flukes.

Although it is not approved for use on goats in most countries, off-label use seems to be quite common, possibly due to the fact that resistance of gastrointestinal roundworms in goats is as serious as in sheep in many countries. In 2012 the EU approved an MRL for monepantel on goats, but to our knowledge this has not resulted so far in label extensions to include goats in the indications for ZOLVIX in the major markets.

Monepantel has not been developed for use on cattle, in spite of the fact that resistance of gastrointestinal roundworms to the available anthelmintics (mainly benzimidazoles, levamisole, macrocyclic lactones and salicylanilides) is becoming an increasing problem worldwide. It seems to be related with differences in the pharmacokinetics of monepantel in sheep and cattle.

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.

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.