Amitraz And Ivermectin Flashcards

1
Q

Amitraz is commonly used for??

A

Flea and tick collars
Demodicosis in dog (topical liquid)

Plant insecticides

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2
Q

What species in amitraz contraindicated in?

A

Cats and horses

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3
Q

What chemical class does amitraz belong too?

A

Amidines -> fomamidines

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4
Q

T/F: amitraz is lipophilic and accumulates in adipose tissue

A

False

Is more lipophilic than hydrophilic
Does NOT accumulate in adipose tissue

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5
Q

What are the usual sources of exposure to amitraz?

A

Dermal/oral
Dogs -chewing/ingesting collar
Application of undiluted or too concentrated solution

Inhalation(rare)

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6
Q

How toxic is amitraz ?

A

Slightly toxic
Mild irritant

Stress or certain drugs can increase toxicity

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7
Q

What is the acute LD50 of amitraz in dogs?

A

100mg/kg

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8
Q

Subacute toxicity of amitraz (20mg/kg) can cause what in dogs?

A

CNS sedation

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9
Q

T/F: amitraz is highly absorbed across the skin?

A

False

Dermal absorption in low , less than 10% in dog and pig

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10
Q

What route of exposure can lead to toxicity most often by amitraz?

A

Oral

Has moderate GI absorption
Most will be excreted unchanged through feces, but large dose can lead to acute poisoning

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11
Q

Once metabolized in the liver, most of amitraz is excreted where?

A

Urine

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12
Q

What is the MOA of amitraz?

A

A2-agonist in CNS

A1 and A2-agonist in ANS

MAO inhibitor —> decreased catecholamines (decreased concentration of neurotransmitters)

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13
Q

What are the GI symptoms seen with Amitraz toxicity?

A
Anorexia
Vomiting 
Abdominal pain
Diarrhea 
Reduced gut motility
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14
Q

What are CNS signs associated with amitraz toxicity?

A

Sedation - reduced irritatbility or agitation
Depression
Tremor

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15
Q

What effect does amitraz have on the circulatory system

A

Vasoconstriction and hypertension

Reflex bradycardia
Turns into tachycardia

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16
Q

T/F: amitraz can cause hyperglycemia, polyuria, and hypothermia

A

True

17
Q

What would other DDX be on your list if you suspect amitraz toxicity?

A

Anticholinesterases
-organophosphate/carbamate

Ivermectin

Pyrethrins ??

Rotenone? -inhibits cellular resp?
Fish usually

18
Q

What is the treatment of amitraz toxicity?

A

Decontamination

  • washing skin with soap and water
  • emesis if collar ingested
  • activated charcoal
  • cathartic
  • gastric lavage

Supportive IV fluids

A2-antagonists

  • yohimbine
  • atipamezole
19
Q

What is the prognosis for amitraz toxicity?

A

Fair to poor depending on symptoms
Good if responds to treatment
Poor if no treatment response

20
Q

What is the MOA of Ivermectin ?

A

GABA agonist —> induce neurological damage by binding to glutamate gated chloride ion channels in nerve and muscle in invertebrates causing paralysis and death

21
Q

What is Ivermectin generally used for?

A

Broad spectrum antiparasitic agent - kills internal and external parasites

Cattle, swine, and sheep- ectoparasite control

Dog and Cat- heartworm

22
Q

T/F: Ivermectin generally does not cross the BBB

A

True

Can cross in cases of genetic defect eg collies

“White feet, don’t treat”

23
Q

How are dogs/cats usually exposed to toxic levels of Ivermectin ?

A

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

24
Q

Why are collies and beagles sensitive to Ivermectin ?

A

Multi-drug resistance MDR) mutant dogs

ABCB1(MDR1) gene mutation —> defective P-glycoproteins —> dysfunctional BBB

25
Q

T/F: ivermectin is absorbed orally well in cats and dogs

A

True

Up to 95%
-ruminants only absorbed 25-33% via oral route

26
Q

T/F: dogs have lower bioavailability of ivermectin than cats, therefore dogs require higher doses

A

False

Cats have lower bioavailability and require higher doses

27
Q

Ivermectin is mostly excreted??

A

In feces

28
Q

What are the clinical signs of ivermectin toxicity ?

A

CNS depression

Mydriasis, blindness, vomiting and drooling, weakness, stupor, recumbency, ataxia, and coma

29
Q

How do you treat for ivermectin toxicity?

A

Decontamination

  • washing
  • emesis
  • activated charcoal
  • saline cathartic

Supportive care

  • fluid, nutritional
  • monitor/treat pressure sores
  • monitor ventilation
  • treat possible bradycardia
30
Q

What is the prognosis of ivermectin toxicity?

A

Depends on exposure

Guarded if clinical signs are rapid onset

Generally no long term adverse effects