Amitraz And Ivermectin Flashcards
(30 cards)
Amitraz is commonly used for??
Flea and tick collars
Demodicosis in dog (topical liquid)
Plant insecticides
What species in amitraz contraindicated in?
Cats and horses
What chemical class does amitraz belong too?
Amidines -> fomamidines
T/F: amitraz is lipophilic and accumulates in adipose tissue
False
Is more lipophilic than hydrophilic
Does NOT accumulate in adipose tissue
What are the usual sources of exposure to amitraz?
Dermal/oral
Dogs -chewing/ingesting collar
Application of undiluted or too concentrated solution
Inhalation(rare)
How toxic is amitraz ?
Slightly toxic
Mild irritant
Stress or certain drugs can increase toxicity
What is the acute LD50 of amitraz in dogs?
100mg/kg
Subacute toxicity of amitraz (20mg/kg) can cause what in dogs?
CNS sedation
T/F: amitraz is highly absorbed across the skin?
False
Dermal absorption in low , less than 10% in dog and pig
What route of exposure can lead to toxicity most often by amitraz?
Oral
Has moderate GI absorption
Most will be excreted unchanged through feces, but large dose can lead to acute poisoning
Once metabolized in the liver, most of amitraz is excreted where?
Urine
What is the MOA of amitraz?
A2-agonist in CNS
A1 and A2-agonist in ANS
MAO inhibitor —> decreased catecholamines (decreased concentration of neurotransmitters)
What are the GI symptoms seen with Amitraz toxicity?
Anorexia Vomiting Abdominal pain Diarrhea Reduced gut motility
What are CNS signs associated with amitraz toxicity?
Sedation - reduced irritatbility or agitation
Depression
Tremor
What effect does amitraz have on the circulatory system
Vasoconstriction and hypertension
Reflex bradycardia
Turns into tachycardia
T/F: amitraz can cause hyperglycemia, polyuria, and hypothermia
True
What would other DDX be on your list if you suspect amitraz toxicity?
Anticholinesterases
-organophosphate/carbamate
Ivermectin
Pyrethrins ??
Rotenone? -inhibits cellular resp?
Fish usually
What is the treatment of amitraz toxicity?
Decontamination
- washing skin with soap and water
- emesis if collar ingested
- activated charcoal
- cathartic
- gastric lavage
Supportive IV fluids
A2-antagonists
- yohimbine
- atipamezole
What is the prognosis for amitraz toxicity?
Fair to poor depending on symptoms
Good if responds to treatment
Poor if no treatment response
What is the MOA of Ivermectin ?
GABA agonist —> induce neurological damage by binding to glutamate gated chloride ion channels in nerve and muscle in invertebrates causing paralysis and death
What is Ivermectin generally used for?
Broad spectrum antiparasitic agent - kills internal and external parasites
Cattle, swine, and sheep- ectoparasite control
Dog and Cat- heartworm
T/F: Ivermectin generally does not cross the BBB
True
Can cross in cases of genetic defect eg collies
“White feet, don’t treat”
How are dogs/cats usually exposed to toxic levels of Ivermectin ?
Extra-label use for other parasites
- large animal products on small animals
- dosing errors
Grooming (cats)
Large amount can be excreted in feces of horses, cows, and pigs
Younger animals highly susceptible
Why are collies and beagles sensitive to Ivermectin ?
Multi-drug resistance MDR) mutant dogs
ABCB1(MDR1) gene mutation —> defective P-glycoproteins —> dysfunctional BBB
