Description
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.
Description
Selamectin is a macrocyclic lactone derivative of ivermectin, an anthelmintic that potentiates glutamate- and GABA-gated chloride channel opening in nematodes. At 0.1 μg/ml, selamectin is reported to inhibit growth in an
H. contortus larval development assay.
Uses
Selamectin is a topical parasiticide and also used as a veterinary antihelminithic agent on animals.
Uses
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.
Definition
ChEBI: Selamectin is a milbemycin.
Hazard
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.
Mechanism of action
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.
Veterinary Drugs and Treatments
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).
Toxicity evaluation
Acute oral LD
50 for rats: >1,600 mg/kg
