The U.S. Food and Drug Administration has issued an emergency use authorization for nitenpyram, allowing the medication to be used to treat New World screwworm infestations in dogs and cats. The move marks the first time a generic animal drug has been cleared for use against the flesh-eating parasite.
According to an FDA statement released Thursday, nitenpyram tablets may be given to dogs and cats that are at least four weeks old and weigh no less than two pounds. The drug was originally approved by the agency in 2000 under the brand name Capstar for the treatment of fleas.
The FDA uses emergency use authorizations to make potentially needed treatments available more quickly when urgent health situations arise.
Unlike insects that feed on dead tissue, New World screwworm larvae consume living flesh and bodily fluids. After mating once during their lifespan, female flies deposit eggs in open wounds or mucous membranes. The resulting larvae can infect any warm-blooded animal, including pets, livestock, wildlife and, in rare cases, humans.
An FDA fact sheet cites studies from Brazil involving dogs and cats with screwworm infestations, showing that most maggots were expelled following treatment with nitenpyram and that those remaining later died. Even so, the agency said Thursday that animals given the tablets may still require veterinary removal of any live or dead larvae left behind.
New World screwworm was once a recurring warm-weather threat for U.S. cattle ranchers from the 1930s through the 1960s and had long been considered eradicated in the country. But government officials have recently reported several new infections in Texas cattle, along with a confirmed case in a dog in New Mexico.
“Nitenpyram works quickly, killing most [screwworm] larvae within hours of the first dose,” the FDA said on Thursday. “Pet owners should administer a second dose six hours after the first.”
However, because the drug’s effects are short-acting, it does not provide ongoing protection against new infestations, the agency added.
