Amitraz/Ivermectin Flashcards
what are the main reasons we use amitraz?
- rapid action against ectoparasites such as ticks and mites
- can control all life stages
- used in beekeeping to control Varroa mite
what is the MOA of amitraz?
- kills by interfering with nervous system
- octopamine receptor antagonist
- works as repellent (detachment effect)
what are the main CS with amitraz toxicity?
- hyperexcitability, paralysis, death
in what species is amitraz contraindicated in?
cats and horse
what are some uses of amitraz?
- used in flea and tick collars
- topical liquid
- generalized demodicosis in dogs
- ascaricide/tickicide for swine and cattle
does amitraz bioaccumulate in the fat?
no
what are the toxicokinetics of amitraz?
- dermal absorption is low (less than 10% in dogs and pigs)
- not readily absorbed into tissues, but quickly distributed throughout the body including the brain
- GIT absorption is moderate - most is quickly excreted unchanged
- rapidly metabolized in liver and excreted in urine
what are the 3 MOAs for amitraz in mammals/vertebrates?
- alpha adrenergic receptor agonist
- alpha 2 agonist in CNS
- alpha 1 and alpha 2 agonist in PNS
- increase in epinephrine, NE, and dopamine
- neurotoxic and preconvulsant effects - inhibition of monoamine oxidases
- can lead to suppression of insulin in dogs
- also increases NTs - inhibits synthesis of PGs
- inhibits synthesis from arachidonic acid
what is the MOA of amitraz with arthropods?
interaction with octopamine receptors
- toxic effects on arthropods, less so on vertebrates
- this receptor is less sensitive in vertebrates
- kills by interfering with nervous system
- tick’s sharp barbed mouth becomes paralyzed and cannot pierce skins so it falls off
what are the main CS seen with amitraz toxicity?
- hyperglycemia
- hypothermia
- PU
- anorexia
- vomiting
- diarrhea
- depression
- tremors
- bradycardia
ultimately can lead to CV collapse and rep failure
how do we treat amitraz toxicity?
- decontaminate
- if collar ingested: induce emesis and/or remove, activated charcoal, cathartics, gastric lavage
- supportive care
- ANTIDOTE: alpha2 antagonists = yohimbine or atipamezole
what is the MOA of ivermectin?
gaba agonist
- induces neurological damage by binding to glutamate gates chloride ion channels in nerve and muscle cells of invertebrates that results in paralysi and death
what is the main use of ivermectin?
broad spectrum antiparasitic agent
- kills a wide range of internal and external parasites in commercial livestock and companion animals
- GI roundworms, lungworms, heartworms, mites, lice, and horn flies
how are animals exposed to ivermectin?
- extra label use for parasites in dogs/cats
- formulation errors are most common
- excessive licking after a pour on
what is the gene mutation resulting in multi-drug resistance?
- ABCB1/MDR1 gene codes for P-glycoprotein
- dogs will have a dysfunctional BBB
- don’t treat
