Ivermectin/Amitraz

Question 1

What is ivermectin?

Answer 1

Broad spectrum antiparasitic agent that kills a wide range of internal and external parasites in commercial livestock and companion animals

Question 2

Does ivermectin cross the BBB?

Answer 2

NO

***unless there is a genetic defect

Question 3

What will quickly degrade ivermectin?

Answer 3

Water and sunlight

Half life is 12-40 hrs

Question 4

What animals use ivermectin extra label?

Answer 4

dogs and cats (for specific parasites)

Ex: ivermectin is not considered extra label in canine HWP

Question 5

horses, cows, and pigs can excrete large amounts of ivermectin in ______

Answer 5

feces

then if a dog ingests that – can be toxic

Question 6

What gene mutation can cause a sensitivity to ivermectin?

Answer 6

MDR1 gene mutation - these patient s will have a defective P-glycoprotein pump –> delayed excretion

***aus. sheps, shelties, collies

Question 7

What is the primary mode of excretion of ivermectin?

Answer 7

45% is unchanged and excreted in the feces
2% excreted in the urine

(elimination half like 2-3 days depending on the formulation)

Question 8

What is the MOA of ivermectin?

Answer 8

Primarily acts as GABA agonist- chlorinated alicyclics

–> increase flow in chloride ions in the neurons –> hyperpolarizes the cell decreasing neuronal transmission that results in CNS depression

Question 9

What is the prognosis of ivermectin toxicosis?

Answer 9

Depends on the exposure

Guarded, if clinical signs are of rapid onset (indicative of high exposure)

Question 10

What animals is amitraz NOT labeled for?

Answer 10

cats and horses

This is an ingredient found in tick collars and in mitaban dip

Question 11

Amitraz toxicity is associated with depression of the ______

Answer 11

CNS

Question 12

What is the mechanism of action of amitraz?

Answer 12

alpha 2 adrenergic agonist in the CNS

alpha 1 and alpha 2 agonist in the peripheral and autonomic nervous system

Weak monoamine oxidase inhibitor –> resulting in an increase in concentration of inhibitory neurotransmitters

Question 13

What is the ultimate cause of death in a patient with amitraz poisoning?

Answer 13

CV collapse and respiratory failure

Question 14

what is the prognosis for amitraz poisoning?

Answer 14

fair to poor (depending on clinical signs)

Question 15

Amitraz can ultimately result in _____ collapse and _______ failure

Answer 15

CV collapse

Respiratory failure

Question 16

What CNS and CV signs will be seen in patients with amitraz toxicosis?

Answer 16

CNS: Sedation, depression, tremors

CV: hypotension, bradycardia

Question 17

What can be used as an antidote to amitraz?

Answer 17

Alpha 2 antagonists: Yohimbine and atipamezole

Question 18

What is the most common way dogs and cats are exposed to ivermectin toxicity?

Answer 18

Dosing errors

Question 19

In which species is ivermectin more bioavailable, dogs or cats?

Answer 19

Dogs

Cats will require higher doses