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CVM GFI #276 Effectiveness of Anthelmintics: Specific Recommendations for Products Proposed for the Prevention of Heartworm Disease in Dogs November 2022


Not for implementation. Contains non-binding recommendations.

This guidance is being distributed for comment purposes only.

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Although you can comment on any guidance at any time (see 21 CFR 10.115(g)(5)), to ensure that the FDA considers your comment on a draft guidance before it begins work on the final version of the guidance, submit either online or written comments on the draft guidance before the close date.

If unable to submit comments online, please mail written comments to:

Dockets Management
Food and Drug Administration
5630 Fishers Lane, Rm 1061
Rockville, MD 20852

All written comments should be identified with this document's docket number: FDA-2022-D-2899

Docket Number:
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Guidance Issuing Office
Center for Veterinary Medicine

The recommended approach to demonstrate substantial evidence of effectiveness of an investigational new animal drug intended for the prevention of heartworm disease in dogs is for the sponsor to conduct two laboratory dose confirmation studies and one multi-site field effectiveness study in accordance with the principles of Good Clinical Practice (GCP) as described in GFI #85 (VICH GL9), “Good Clinical Practice.’’   Laboratory dose confirmation studies are experimentally-induced infection studies that provide known exposure to infectious Dirofilaria immitis (D. immitis) larvae (L3) due to contemporaneous experimental infection of the same number of L3 to negative control dogs and dogs administered the investigational new animal drug.  Laboratory dose confirmation studies also allow for quantitative evaluation of outcome by determining the presence of adult worms as well as the individual worm burden in each dog.

The field effectiveness study evaluates the effectiveness of the investigational new animal drug under actual conditions of use in client-owned dogs and with the current enzootic status, ecologic, and genetic factors affecting heartworm disease in dogs in each location.

FDA’s recommended approach considers the laboratory dose confirmation studies and the field effectiveness study together when evaluating if substantial evidence of effectiveness (21 CFR 514.4) and inferential value to the target population have been met. 


Contact Point
Steven Fleischer
Center for Veterinary Medicine
Food and Drug Administration
7500 Standish Place, HFV-110
Rockville, MD 20855
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