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==Introduction==
==Introduction==
This group of drugs are derived from ''Streptomyces'' species and are coded as '''3-AV''' products. They are commonly known as '''avermectins''' and '''milbemycins'''. Drugs in use include; '''ivermectin, abamectin, doramectin, moxidectin, eprinomectin''' and '''selamectin'''.
This group of drugs are derived from ''Streptomyces'' species and are coded as '''3-AV''' products. They are commonly known as '''avermectins''' and '''milbemycins'''. Drugs in use include; '''ivermectin, abamectin, doramectin, moxidectin, eprinomectin''' and '''selamectin'''.
==Activity==
==Activity==
* They are inactive against trematodes, cestodes and adult filarial worms. Though are active against migrating heart worm larvae and are used as heartworm prophylactics in cats and dogs.
* They are inactive against trematodes, cestodes and adult filarial worms. Though are active against migrating heart worm larvae and are used as heartworm prophylactics in cats and dogs.
* Their mode of action is by opening invertebrate specific glutamate-gated chloride channels on the post-synaptic membranes. This results in '''flaccid paralysis''' of the parasite.
* Their mode of action is by opening invertebrate specific glutamate-gated chloride channels on the post-synaptic membranes. This results in '''flaccid paralysis''' of the parasite.
==Pharmacokinetics==
==Pharmacokinetics==
They can be '''metaphylactic''' and be given mid-season, thus protecting animals grazing on contaminated pastures.
They can be '''metaphylactic''' and be given mid-season, thus protecting animals grazing on contaminated pastures.
* Due to this long tail on the plasma curve, the product remains in the animal's body longer than most. This means that its meat and milk withdrawal periods are longer than other anthelmintics. Eprinomectin is the exception is used in dairy cows as it isn't excreted in milk.
* Due to this long tail on the plasma curve, the product remains in the animal's body longer than most. This means that its meat and milk withdrawal periods are longer than other anthelmintics. Eprinomectin is the exception is used in dairy cows as it isn't excreted in milk.
==Safety==
==Safety==