220119-17-5

Selamectin is formulated as a spot-on for cats and dogs to control fleas (Ctenocephalides spp.) and flea-allergy dermatitis, to prevent heartworm disease, and to control ear mites (Otodectes cynotes) in cats and dogs. It is also approved for the treatment and control of sarcoptic mange (Sarcoptes scabiei) in dogs and hookworms (Ancylostoma tubaeformis) and roundworms (Toxocara cati) in cats.

Selamectin is a semi-synthetic avermectin derivative prepared by selective hydrolysis and oximation of doramectin. Selamectin is a potent nematocide used for the treatment of endo- and exo- parasites of domestic animals, notably cats and dogs. Like the other milbemycin/avermectins, selamectin selectively binds to parasite glutamate-gated chloride ion channels and disrupts neurotransmission leading to paralysis and death of the parasite.

Selamectin is a topical parasiticide and also used as a veterinary antihelminithic agent on animals.

ChEBI: Selamectin is a milbemycin.

Selamectin is a veterinary drug for the prevention or treatment of internal and external parasites in cats and dogs and is not approved for use in humans. It is a very safe drug, but overdose or accidental exposure may result in poisoning. In rare cases, humans may experience skin reactions such as hives, itching and redness of the skin.

Selamectin is a semi-synthetic avermectin that belongs to the class of macrolides. These drugs are neurotoxic to the parasite by enhancing glutamate-gated chloride ion channels in the parasite. The parasite becomes paralysed and dies due to increased permeability of chloride ions and hyperpolarisation of nerve cells. These drugs also potentiate other chloride channels, including those gated by gamma-aminobutyric acid (GABA). Mammals are usually unaffected because they lack glutamate-gated chloride channels and have a lower affinity for other mammalian chloride channels. Since these drugs do not normally penetrate the blood-brain barrier, GABA-gated channels in the mammalian CNS are not affected. Following topical administration, Selamectin has a high affinity for sebaceous glands and skin.

Topical selamectin (Revolution?—Pfizer) is indicated for flea infestations (Ctenocephalides felis), prevention of heartworm disease (Dirofilaria immitis), and for ear mites (Otodectes cynotis) in both dogs and cats. Additionally in dogs, it is indicated for sarcoptic mange (Sarcoptes scabeii), and tick infestations (Dermacentor variabilis). In cats: hookworm (Ancylostoma tubaeforme) and roundworm (Toxocara cati). The product (Revolution?) is labeled as not effective against either adult heartworms or clearing circulating microfilaria, but it possibly may have some efficacy with prolonged, continuous administration (Atkins 2007b).

Store at -20°C

Acute oral LD₅₀ for rats: >1,600 mg/kg