Silver Spring, Maryland, USA, September 3, 2026
The U.S. Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for Capstar (nitenpyram) tablets and revised the existing EUA for generic Nitenpyram Tablets to allow both products to prevent and treat New World screwworm (NWS) infestations in dogs, puppies, cats and kittens. The action addresses a significant unmet need in veterinary medicine, because previously authorized products for dogs and cats were available for treatment but not prevention. The FDA said the authorized products may be effective against New World screwworm myiasis, an infestation caused by the larvae of Cochliomyia hominivorax, when used according to the emergency authorization. The products are authorized for animals weighing at least two pounds and at least four weeks of age.
FDA Expands Prevention and Treatment Options
The FDA’s latest action gives veterinarians and pet owners additional tools to address the threat of New World screwworm, a parasitic fly whose larvae can infest wounds and other openings in warm-blooded animals. The larvae feed on living tissue and can cause serious injury, making rapid veterinary intervention important when an infestation occurs. The agency noted that most dogs and cats in the United States currently have a low risk of exposure, because confirmed NWS cases remain concentrated in limited geographic areas. However, risk can increase for pets that live in, travel to or return from regions where infestations have been identified by animal-health authorities. Under the new authorization, Capstar and Nitenpyram Tablets can be used for both prevention and treatment in eligible dogs, puppies, cats and kittens. Nitenpyram Tablets had previously received an EUA in June 2026 for treatment only, making the September revision an important expansion of its authorized use. The FDA concluded, based on the totality of available scientific evidence, that it is reasonable to believe the products may be effective and that their known and potential benefits outweigh their known and potential risks under the authorized conditions.
Nitenpyram Provides Oral Veterinary Treatment
Both products are available over the counter and are supplied in 11.4 mg and 57 mg tablet strengths, with dosing determined by the animal’s body weight. The FDA specifically states that the products should not be administered to dogs, puppies, cats or kittens weighing less than two pounds or younger than four weeks of age. The emergency authorization provides a regulatory mechanism for rapid access to animal-health products during the NWS emergency rather than representing a conventional full approval for this indication. This distinction is important for veterinary professionals and pet owners. The FDA’s veterinary guidance explains that an Emergency Use Authorization is different from full animal-drug approval or conditional approval. Currently, the agency reports that no animal drugs have received full FDA approval specifically for NWS myiasis, while several products have received conditional approvals or EUAs to address the emergency. For treatment of an active infestation, veterinary care remains essential because physical removal of screwworm larvae from wounds may also be required. Pet owners should seek immediate veterinary attention when signs such as visible maggots or unusual odors from wounds or body openings are observed.
Advertisement
Emergency Authorization Strengthens Animal Health Response
The FDA’s decision forms part of a broader federal effort to expand access to animal drugs for New World screwworm. As of September 3, 2026, the agency reported issuing 15 Emergency Use Authorizations and three conditional approvals for animal drugs targeting NWS. These regulatory actions complement other disease-control measures, including surveillance, animal management and the sterile fly program, which are being used to address the broader threat posed by the parasite. The latest EUA therefore represents an important development for veterinary pharmaceutical preparedness. By expanding both prevention and treatment options for companion animals, the FDA is addressing a critical gap in animal-health protection while responding to an emerging disease threat. The authorizations will remain in effect until they are revoked or the relevant federal emergency declaration is terminated. For the veterinary pharmaceutical sector, the decision also demonstrates how emergency regulatory pathways can accelerate access to potentially important animal medicines when conventional development and approval timelines may not adequately address an urgent animal-health threat.
Source: FDA press release
