FDA authorizes use of generic nitenpyram for screwworm in dogs and cats

Although the risk of NWS in US pets is generally low, it has increased for those recently in areas with confirmed cases

The U.S. Food and Drug Administration (FDA) on June 11 issued an Emergency Use Authorization (EUA) for generic nitenpyram tablets for the treatment of New World screwworm (NWS) infestations (myiasis) in dogs, puppies, cats and kittens that weigh at least two pounds and are at least 4 weeks old. This is the first generic animal drug that a U.S. government agency has authorized for use against NWS. It is available for purchase over the counter.

[Ed: Since many horse owners are also pet owners, we are sharing the details here. Nitenpyram is an insect neurotoxin sometimes used to treat adult flea infestations in both cats and dogs. The active ingredient in products such as Capstar® and Bestguard®, it is also notable for its effectiveness against fly larvae.]

Potential benefits believed to outweight risks

The FDA has concluded that based on the totality of the scientific evidence available, it is reasonable to believe that nitenpyram tablets may be effective in the treatment of NWS myiasis in certain dogs, puppies, cats and kittens, and the known and potential benefits of the product outweigh its known and potential risks.

“The FDA has spent nearly a year fast-tracking reviews and readying for the arrival of New World screwworm in the U.S.,” said Acting FDA Commissioner Kyle Diamantas. “As of today … the FDA has issued 10 EUAs and three conditional approvals for drugs to combat this threat, and this count will continue to grow as we receive more animal drug submissions and unleash American regulatory speed.”

“[We are] taking a whole of government approach to fighting New World screwworm. USDA has been working with our partners to prepare for this day and were ready day one to spring into action,” said U.S. Department of Agriculture Secretary Brooke Rollins. “HHS and FDA have been great partners in this fight, and I am thankful to Secretary Kennedy for making sure cat and dog owners have access to treatment should they need it.”

“Generic animal drugs build resilience in our domestic supply chain and play a critical role in expanding the toolkit of U.S. veterinary drugs for New World screwworm,” said Timothy Schell, Ph.D., director of the FDA’s Center for Veterinary Medicine. “By authorizing this generic treatment, FDA is reinforcing our commitment to providing timely, affordable options to safeguard animal health for American pet owners.”

Administration and follow-up

NWS flies lay eggs in open wounds or mucous membranes of mammals and the larvae hatch within hours and burrow into the animal’s flesh. Nitenpyram works quickly, killing most NWS larvae within hours of the first dose. Pet owners should administer a second dose six hours after the first. Because the effects are short-acting, nitenpyram tablets do not prevent NWS myiasis or protect against reinfestation.

Following treatment with nitenpyram tablets, a veterinary professional may need to physically remove any remaining live or dead larvae. Someone with veterinary training should perform this task to minimize the risk of infection or further tissue damage. Pet owners are advised to consult a veterinarian about appropriate wound care and how to minimize the risk of reinfestation.

Nitenpyram tablets are available over the counter and come in two tablet sizes: 11.4 and 57 mg. Dosage is based on a dog’s or cat’s weight. Do not administer to pets less than two pounds.

Information on Nitenpyram

Detailed product information about nitenpyram tablets can be found in the Fact Sheet: Emergency Use Authorization of Nitenpyram Tablets (nitenpyram) for New World Screwworm (NWS). Refer to the package insert for safety information related to redosing, use in pregnant or nursing dogs and cats, and use together with other products.

Nitenpyram tablets are sponsored by Felix Pharmaceuticals Pvt. Ltd., which is based in Ireland.

For more information call the FDA’s Consumer line at (888) INFO-FDA.

About the FDA

The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements and radiation-emitting electronic products, and for regulating tobacco products.