What is an active ingredient?

An active ingredient in a pharmaceutical or veterinary medicine is the chemical compound or substance that is biologically active. In a parasiticide the active ingredient is the substance that kills the parasites. The active ingredient is also called "active substance" or "active compound".

Besides the biologically active ingredient all veterinary parasiticides contain other biologically inactive or inert ingredients, also called excipients.

Altogether the active ingredients and the inert ingredients build the formulation. Each veterinary (or human) medicine or parasiticide has its own formulation, i.e. its own recipe or composition. For many products, not only the composition is important, but also the way and sequence the ingredients are mixed together during manufacturing.

Particular medicines or pesticides sometimes contain a mixture of different active ingredients. This is usually done to target more parasites species, i.e. to ensure a broader spectrum of activity.

The amount of active ingredient in a particular product varies a lot. It ranges between 1% or less (e.g. injectables with macrocyclic lactones) and more than 50% (e.g. some feed additives or some concentrates for spraying or dipping, etc).

The inert ingredients that can make up to 99% and more of the finished product, are often not only just passive ingredients (e.g. water as solvent in a liquid product, or a cellulose derivative as binder in a tablet), but accomplish several functions that can be essential for product efficacy, safety and quality. Such inert ingredients can be e.g.

  • Dispersants: keep particles suspended and prevent their settling or clogging.
  • Emulsifiers: encourage the suspension of one liquid in another one (e.g. oil in water).
  • Stabilizers: prevent chemical reactions between the ingredients.
  • Preservatives: prevent the growth of undesired microorganisms in the product.
  • etc.

Inert ingredients can also have a significant influence on whether a finished parasiticide is flammable, explosive, corrosive, irritant to the eyes or the skin, etc.

Naming of Active Ingredients

Active ingredients are mostly refered to with their "common name". It is useful to know (especially when searching information in the web) that all active ingredients have also an official "chemical name", which itself varies according to several international bodies. Just one example:

  • Common name: cypermethrin
  • Chemical name: according to IUPAC: (RS)-alpha-cyano-3-phenoxybenzyl (1RS) cis-trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane carboxylate
  • Chemical name: according to CAS: (RS)-cyano (3-phenoxyphenyl) methyl (1RS) - cis-trans-3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropane carboxylate
  • Other chemical names: (according to www.pesticideinfo.org) 02171 (CA DPR Chem Code Text) , 02171 (CA DPR Chem Code) , 109704 (US EPA PC Code Text) , 109704 (US EPA PC Code) , 2171 (CA DPR Chem Code) , 2171 (CA DPR Chem Code) , 52315-07-8 (CAS number) , 52315078 (CAS number without hyphens) , 597 (PDP Code) , 66841-24-5 (CAS number) , 66841245 , 66841245 (CAS number without hyphens) , Cipermetrin , Cipermetrina , Cyclopropanecarboxylic acid, 3-(2,2-dichloroethenyl)-2,2-dimethyl-, (R)-cyano(3-phenoxyphenyl)methyl ester, (1R, 3S)- , Cyclopropanecarboxylic acid, 3-(2,2-dichloroethenyl)-2,2-dimethyl-, cyano(3-phenoxyphenyl)methyl ester , Cyclopropanecarboxylic acid, 3-(2,2-dichloroethenyl)-2,2-dimethyl-, cyano(3-phenoxyphenyl)methyl ester, 1R-1alpha(R*),3beta- , cypermethin , Cypermethrin, Cypermethrine , d-trans-.beta.Cypermethrin

In most brands, the product labels indicate the content of active ingredient using the "common name". However, there are some smart manufacturers that don't use the "common name" in the product label but one of the numberless "chemical names". Maybe it's their way of implementing the number 4 marketing rule: "be different". Rule numbers 1 to 3 "be new", "be superior" and "be unique" are quite hard to achieve with generic active ingredients, which is what >95% of the antiparasitic brands contain.

Active ingredients with parasiticidal efficacy for veterinary use

This section of parasitipedia.net includes TECHNICAL DATASHEETS of the active ingredients most widely used in veterinary antiparasitics, i.e. against external parasites (e.g. flies, fleas, ticks, mites, etc.) and/or parasitic worms (roundworms, tapeworms, flukes) of livestock (cattle, sheep, goats, pig, poultry) and pets (dogs and cats).

You can select a particular active ingredient in the table below or in the corresponding menu.

LEGEND (1) Decade + Company that introduced it.


Chemical class

Introduced by (1)

Abamectin Macrocyclic Lactone 1980s Am. Cyanamid, Shell
Afoxolaner Isoxazoline 2010s Merial (Du Pont)
Albendazole Benzimidazole 1970s Smith-Kline 
Alphamethrin Synthetic Pyrethroid 1980s ?
Amitraz Amidine 1970s Boots & Co, Camco 
Azadirachtin Natural compound Various
Azamethiphos Organophosphate 1970s Ciba-Geigy
Carbaryl Carbamate 1950s Union Carbide
Carvacrol Natural compound Various
Chlorfenvinphos Organophosphate 1960s Ciba-Geigy, Shell
Chlorpyrifos Organophosphate 1960s Dow Chemical
Citronellal Natural compound Various
Clorsulon Sulphonamide 1970s MS&D Agvet
Closantel Salicylanilides 1970s Janssen
Coumaphos Organophosphate 1950s Bayer
Cyfluthrin Synthetic Pyrethroid 1980s Bayer
Cyhalothrin Synthetic Pyrethroid 1980s ICI
Cymiazol Amidine 1970s Ciba-Geigy
Cypermethrin  Synthetic Pyrethroid  1970s Ciba-Geigy, ICI, Shell
Cyphenothrin Synthetic Pyrethroid 1980s Sumitomo
Cyromazine  Development Inhibitor 1970s Ciba-Geigy
D-limonene Natural compound Various
Dichlorophen Phenol derivative ?
DDVP =Diclorvos Organophosphate 1950s Bayer, Ciba-Geigy, Shell
Deltamethrin Synthetic Pyrethroid 1970s Roussel Uclaf
Diazinon = Dimpylate Organophosphate 1950s Ciba-Geigy
Derquantel Spiroindole 2010s Zoetis
Dichlorvos =DDVP Organophosphate  1960s Bayer, Ciba-Geigy, Shell
Dicyclanil Development Inhibitor 1990s Novartis
Diflubenzuron Development Inhibitor 1970s Philips-Duphar
Dinotefuran Neonicotinoid 1990s Mitsui
Doramectin Macrocyclic Lactone 1990s Pfizer
Dimpylate =Diazinon Organophosphate 1950s Ciba-Geigy
Emodepside Depsipeptide 1990s Bayer
Eprinomectin Macrocyclic Lactone 1990s MS&D Agvet
Epsiprantel Isoquinoline 1990s Pfizer
Ethion Organophosphate 1950s FMC
Etofenprox Synthetic Pyrethroid 1980s Mitsui
Eucalyptol Natural compound Various
Eugenol Natural compound Various
Febantel Pro-Benzimidazole 1970s Bayer
Fenbendazole Benzimidazole 1970s Hoechst
Fenitrothion Organophosphate 1950s Bayer, Sumitomo
Fenthion Organophosphate 1960s Bayer
Fenvalerate Synthetic Pyrethroid 1970s Shell, Sumitomo
Fipronil Phenylpyrazole 1990s Rhône-Mérieux
Fluazuron Development Inhibitor  1990s Novartis
Flubendazole Benzimidazole  1970s Janssen
Flumethrin Synthetic Pyrethroid 1970s Bayer
Fluralaner Isoxazoline 2010s MSD AH (Nissan)
Geraniol Natural compound Various
Imidacloprid  Neonicotinoid  1990s Bayer
Indoxacarb Oxadiazine 2000s DuPont
Ivermectin  Macr. Lactone  1980s MS&D Agvet
Levamisole Imidazothiazole 1960s Janssen
Linalool Natural compound Various
Lindane Organochlorine 1940s ICI


Isoxazoline 2010s Elanco
Lufenuron Development Inhibitor 1990s Ciba-Geigy
Malathion Organophosphate 1950s Am. Cyanamid 
Mebendazole Benzimidazole 1970s Janssen
Metaflumizone Semicarbazone 2000s BASF
Methomyl Carbamate 1960s Du Pont
Methoprene Development Inhibitor 1970s Zoecon
Metrifonate =Triclorphon Organophosphate 1950s Bayer
Milbemycin oxime Macrocyclic Lactone 1990s Ciba-Geigy
Monepantel Amino-acetonitrile der. 2000s Novartis
Morantel Tetra-hydropyrimidine 1960s Pfizer
Moxidectin Macrocyclic Lactone 1990s Am. Cyanamid
Netobimin Pro-Benzimidazole 1980s Shering Plough
Niclosamide Salicylanilide 1960s Bayer
Nitenpyram Neonicotinoid 1990s Takeda, Novartis
Nitroscanate  Isothiocyanate  1970s Ciba-Geigy
Nitroxinil Halogenated phenol 1960s May & Baker
Oxantel Tetra-hydropyrimidine 1970s Pfizer
Oxfendazole Benzimidazole 1970s Wellcome, Syntex
Oxibendazole Benzimidazole 1970s Smith Kline
Oxyclozanide Salicylanilide 1960s ICI
Permethrin Synthetic Pyrethroid 1970s FMC, ICI, Shell, Sumit.
Phenothrin Synthetic Pyrethroid 1980s Sumitomo
Phosmet Organophosphate  1960s Stauffer
Phoxim  Organophosphate   1960s Bayer
Piperazine Piperazine derivative 1950s Shering
Praziquantel Isoquinoline 1970s Bayer
Propoxur  Carbamate  1960s Bayer 
Pyrantel Tetra-hydropyrimidine 1960s Pfizer
Pyrethrins Natural compounds Various
Pyriprole Phenylpyrazole 2000s Novartis
Pyriproxyfen Development Inhibitor 1980s Sumitomo
Rafoxanide Salicylanilide 1970s MS&D Agvet
Ricobendazole Benzimidazole  1980s Robert Young
Rotenone Natural insecticide ~1900 Traditional
Sarolaner Isoxazoline 2010s Zoetis
Selamectin Macrocyclic Lactone 1990s Pfizer
Spinetoram  Spinosyns  2000s Dow
Spinosad Spinosyns   1990s Eli-Lilly
Tetramethrin  Synthetic Pyrethroid 1960s Sumitomo
Tetramisole Imidazothiazole 1960s Janssen
Thiabendazole Benzimidazole 1960s MS&D Agvet
Thiamethoxam  Neonicotinoid   1990s Novartis
Thiophanate Pro-Benzimidazole 1970s May & Baker
Thymol Natural compound Various
Trichlorfon = Metrifonate Organophosphate 1960s Bayer
Triclabendazole Benzimidazole 1970s Ciba-Geigy
Triflumuron Development Inhibitor 1980s Bayer

LEGEND. (1) Ecto = insects, ticks, mites, etc.; Endo = roundworms, tapeworms, flukes • (2) L=Livestock; P=Pets (C=Crop protection; Hy=Domestic and Public Hygiene; H=Human) • (3) Decade + Company that introduced it.

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