The variety of veterinary antiparasitic APIs is extensive. They can be classified into the following major categories based on their target and chemical structure:
Primarily used to control internal parasites like nematodes (roundworms), cestodes (tapeworms), and trematodes (flukes).
● Characteristics: Broad-spectrum, highly effective, and safe; one of the most widely used classes of anthelmintics.
● Albendazole: Effective against nematodes, cestodes, and trematodes; commonly used in cattle and sheep.
● Fenbendazole: Broad-spectrum anthelmintic, highly effective against both larvae and adults of gastrointestinal nematodes; high safety profile.
● Oxfendazole: Similar to fenbendazole; it is the metabolically active product of fenbendazole in the body.
● Flubendazole: Highly effective and broad-spectrum; particularly used for deworming pigs and poultry.
● Mebendazole: Effective against nematodes and cestodes.
● Febantel: A pro-drug that is metabolized into fenbendazole in the body to become active.
● Characteristics: Currently the mainstream of highly effective, broad-spectrum, and long-lasting anthelmintics; excellent efficacy against both internal and external parasites.
● Ivermectin: The most renowned product; excellent efficacy against internal nematodes and external arthropods (e.g., mites, lice, fly larvae). Widely used in cattle, sheep, pigs, dogs, etc.
● Avermectin: An analog of ivermectin with slightly lower potency; commonly used in agricultural and veterinary applications.
● Doramectin: Has a longer duration of action than ivermectin, maintaining effective blood concentrations for a longer period.
● Selamectin: Mainly used in dogs and cats; effective against both internal and external parasites; commonly found in topical spot-on formulations.
● Moxidectin: Known for its long-lasting effect; may be effective against some ivermectin-resistant parasite strains.
● Levamisole: Highly effective against gastrointestinal nematodes and lungworms; also possesses immunomodulatory properties.
● Pyrantel: Effective against gastrointestinal nematodes; high safety profile; commonly used in horses, pigs, and dogs.
● Morantel: Similar to pyrantel.
● Praziquantel: Specifically highly effective against cestodes (tapeworms); highly effective against almost all adult and larval stages of cestodes. Often combined with ivermectin or others in broad-spectrum compound formulations.
● Closantel: Highly effective against trematodes (especially liver flukes Fasciola hepatica) and blood parasites (e.g., nasal bot fly larvae Oestrus ovis); also has long-acting parasiticidal effects.
● Triclabendazole: Specifically targets trematodes (flukes); highly effective against all stages of liver flukes; the drug of choice for controlling liver fluke in cattle and sheep.
● Diclazuril: Although primarily used for coccidia, it is also effective against some protozoa (e.g., Toxoplasma) and neosporosis.
Primarily used in poultry (chickens, turkeys) to prevent and control coccidiosis.
● Characteristics: Kill parasites by disrupting ion balance in the cell; less prone to resistance development; mainstream for preventive feed additive use.
● Monensin: The most commonly used ionophore anticoccidial.
● Salinomycin
● Narasin
● Lasalocid
● Characteristics: Diverse modes of action; often used for treatment or in rotation with ionophores to delay resistance.
● Diclazuril: Highly potent, very low dosage required.
● Toltrazuril: Broad-spectrum, effective against all developmental stages of coccidia; often used for treatment.
● Sulfonamides: e.g., Sulfaquinoxaline, Sulfachloropyrazine; primarily used for treatment.
● Amprolium
● Nicarbazin
● Dinitolmide (DOT)
Used to control external parasites such as mites, ticks, lice, and flies on the animal's body surface.
● Characteristics: Strong contact action, fast knockdown, low mammalian toxicity.
● Deltamethrin: Highest potency.
● Fenvalerate
● Beta-cypermethrin
● Flumethrin: Commonly used for dairy cattle and bees.
● Characteristics: Relatively higher toxicity; usage has declined.
● Dichlorvos (DDVP)
● Diazinon
● Malathion
● Amitraz: Broad-spectrum miticide and acaricide (kills mites and ticks); commonly used in cattle, sheep, pigs, and dogs.
● Cyromazine: An insect growth regulator; added to feed to control fly larvae.
● Neonicotinoids: e.g., Imidacloprid; commonly used for flea control in dogs and cats.
● Isoxazolines: Newest generation; highly effective, long-lasting, and good safety profile; excellent efficacy against fleas and ticks via oral or topical administration.
● Afoxolaner - Brand name NexGard
● Fluralaner - Brand name Bravecto
● Sarolaner - Brand name Simparica
● Lotilaner - Brand name Credelio
● Prevalence of Compound Formulations: To broaden the antiparasitic spectrum and delay resistance, compound APIs or formulations are common on the market, such as Ivermectin + Albendazole, Ivermectin + Praziquantel, etc.
● Diversified Formulations: Depending on the animal species and application scenario, APIs are formulated into various dosage forms, such as premixes, injections, topical spot-ons, oral tablets, granules, and pour-ons.
● Resistance Issues: Long-term and irrational use has led to increasing parasite resistance, necessitating scientific antiparasitic rotation programs.
● Withdrawal Time (Period): All veterinary APIs must strictly adhere to withdrawal time regulations to ensure drug residues in animal-derived products (meat, eggs, milk) are below safe limits, guaranteeing food safety.