|Trade names||Cydectin, Equest, ProHeart, Quest.|
|Synonyms||CL 301,423; milbemycin B.|
|AHFS/Drugs.com||International Drug Names|
|oral, topical, subcutaneous|
|Chemical and physical data|
|Molar mass||639.819 g/mol|
|3D model (JSmol)|
|(what is this?)|
Moxidectin is an anthelmintic drug used in animals to prevent or control parasitic worms (helminths), such as heartworm and intestinal worms, in dogs, cats, horses, cattle and sheep. Moxidectin kills some of the most common internal and external parasites by selectively binding to a parasite's glutamate-gated chloride ion channels. These channels are vital to the function of invertebrate nerve and muscle cells; when moxidectin binds to the channels, it disrupts neurotransmission, resulting in paralysis and death of the parasite.
- Dogs: Prevention of heartworm. In combination with imidacloprid to treat sarcoptic mange.
- Horses: Treatment of parasites including Strongylus vulgaris, and stomach bots such as Gasterophilus intestinalis.
- Cattle: Treatment of parasites such as the gastrointestinal nematode Ostertagia ostertagi, and the lungworm Dictyocaulus viviparus.
- Sheep: Treatment of the nematodes Teladorsagia circumcincta and Haemonchus contortus.
Studies of moxidectin show the side effects vary by animal and may be affected by the product’s formulation, application method and dosage.
An overdose of moxidectin enhances the effect of gamma-aminobutyric acid (GABA) in the central nervous system. In horses, overdose may lead to depression, drooping of the lower lip, tremor, lack of coordination when moving (ataxia), decreased rate of breathing (respiratory rate), stupor and coma.
If a dog licks moxidectin from the skin which was applied as a "spot-on" (topical) treatment, this has the same effect as an overdose, and may cause vomiting, salivation and neurological signs such as ataxia, tremor, and nystagmus. Collie dogs cannot be administered moxidectin.
Moxidectin is very lipophilic, which causes it to have a high volume of distribution. Moxidectin concentrates in the animal's adipose tissue, from where it is released for up to two months following administration.
In goats, the oral bioavailability of moxidectin is 2.7 times lower, and the half-life is 1.8 times shorter than in sheep.
Moxidectin, a macrocyclic lactone of the milbemycin class, is a semisynthetic derivative of nemadectin, which is a fermentation product of the bacterium Streptomyces cyanogriseus subsp. noncyanogenus.
In the late 1980s, an American Cyanamid Company agronomist discovered the Streptomyces bacteria from which moxidectin is derived in a soil sample from Australia. Two companies filed patents for moxidectin: Glaxo Group and the American Cyanamid Company; in 1988, all patents were transferred to American Cyanamid. In 1990, the first moxidectin product was sold in Argentina.
Use in humans
Moxidectin has been approved by US FDA for the treatment of onchocerciasis (river-blindness) in people aged 12 years of age and older on the basis of two clinical trials. Moxidectin is predicted to be a helpful tool to achieve elimination goals of this disease. The license holder is the nonprofit biopharmaceutical company Medicines Development for Global Health.
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