Derquantel is used as an anthelmintic agent, primarily in veterinary medicine, to treat parasitic worm infestations in livestock and companion animals. It is especially effective against gastrointestinal nematodes, including resistant strains that do not respond to other classes of dewormers. Derquantel works by targeting the nervous system of parasites, specifically acting as an antagonist at nematode-specific glutamate-gated chloride channels, leading to paralysis and death of the worms. It is often combined with other anthelmintics, such as abamectin, to broaden the spectrum of activity and reduce the risk of resistance development. This combination is commonly formulated in oral drenches for use in sheep and other ruminants. Its use supports improved animal health, weight gain, and productivity in farming operations.