Efficacy standards for veterinary anthelmintics in Australia

The International Cooperation on Harmonisation of Technical Requirements for Registration of Veterinary Medicinal Products (also known as VICH) was officially launched in Paris in April 1996, as a cooperative effort between members of the regulatory authorities and the veterinary chemical industry from the European Union, the United States and Japan. The program aims to harmonise technical guidelines for veterinary product registration, and has drawn on the experience of the human pharmaceutical harmonisation initiative, ICH.

The regulatory authorities of Australia and New Zealand have observer status on the VICH Steering Committee.

To evaluate the efficacy of anthelmintics in bovine, ovine, caprine equine, porcine, canine, feline and poultry, the Australian Pesticides and Veterinary Medicines Authority (APVMA) has adopted guidelines developed by the VICH process, including:

These guidelines are to be used in conjunction with the APVMA’s Part 8 Efficacy and Safety Guidelines, as well as the World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines for evaluating the efficacy of anthelmintics.

VICH GL7 (Anthelmintics General): Efficacy of Anthelmintics: General Requirements should be read in conjunction with the specific guidelines.

There are some differences between VICH/WAAVP recommendations and recommendations for products to be registered in Australia. The VICH and WAAVP guidelines generally consider a mean percentage reduction in parasite numbers of at least 90% to be effective to support a claim. Because suboptimal efficacy can increase selection pressure for resistance, we generally consider at least 95% to be the minimum effective threshold for a claim. In some situations we may consider an even higher threshold of efficacy for a claim (e.g. Dirofilaria immitis, Echinococcus granulosus). We encourage you to use these efficacy standards when generating data for equine, porcine, canine, feline and poultry anthelmintics in Australia.

Because of Australia’s unique environmental and geographical features, farm management practices, animal breeds and parasite burdens and their population dynamics, there are some differences between VICH/WAAVP recommendations and recommendations for products that are to be registered in Australia.

Therefore, the following additional guidance is provided for applicants proposing the registration of ruminant anthelmintics in Australia:

  • You should demonstrate persistent effectiveness at a level of greater than 99% to support your proposed claims.
  • Because of Australia’s history of parasite resistance selection, we recommend that most of the confirmatory field efficacy work be conducted within Australia under typical farm management practices covering relevant geographical regions.
  • If you have efficacy data generated overseas, submit those data at the time of the product registration application.

We encourage you to use the efficacy standards shown in Table 1 when generating data for ruminant anthelmintics in Australia. These criteria are usually sufficient to give us confidence in the product’s efficacy in Australia’s unique conditions. For your reference, Table 1 is specifically related to:

  • Section 5, Standards for effectiveness of VICH GL7; and
  • Section 4.1, Criteria to grant a claim of VICH GL12, 13 and 14.
Table 1: Efficacy standards for anthelmintics in Australia
Parasite Host species Claim for treatment/control Claim for persistent effectiveness
Gastrointestinal helminths and lungworm Sheep/goats >95% >99%
Gastrointestinal helminths and lungworm Cattle >95% >95%
Liver fluke All >90%  

Note on geometric versus arithmetic means

In relation to Section 4.2 Geometric versus arithmetic means of VICH GL7, the geometric mean is appropriate for statistical tests where data is non-normally distributed. However, the geometric mean may underestimate the biological significance of worms in the animals with the highest worm burdens. We consider that the current information on statistics does not support the adoption of geometric means as the sole means of interpreting trial data. If the arithmetic mean for the data provided in efficacy trials shows marked variance from the geometric mean, we may take the arithmetic mean into consideration (that is, we are likely to give more weight to the arithmetic mean when there is variability in the trial data).

The VICH guidelines can also be accessed from the VICH website.

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