Ivermectin Flashcards
What is ivermectin?
Broad spectrum antiparasitic agent that kills a wide range of internal and external parasites in commercial livestock and companion animals
How does ivermectin work?
GABA agonist- induces neurological damage by binding to glutamate-gated chloride ion channels in nerve and muscle cells of invertebrates that results in paralysis and death
True or False. Ivermectin crosses the BBB.
False- unless there is a genetic defect that allows it cross
Which formulations are used as extra-label in cats and dogs that causes many dosing errors?
Formulations for sheep and cattle
How are these animals exposed?
A large amount can be excreted in feces of horses, cows, pigs
-Tx of horse with recommended dosage resulted in 2.4 mg/kg– so if the dog eats feces its a toxic dose to the dog! (Typical dose is 0.006 mg/kg)
True or False. There is a narrow safety margin for ivermectin for dogs.
False. Wide margin
“White Feet, _____________ ______________” this is in reference to what?
Don’t Treat.
The MDR- multi-drug resistance mutant dogs (these dogs have a dysfunctional BBB)
Who has a lower bioavailability, cats or dogs? So what should the dosage for cat or dogs be?
Cats.
Need to have a higher dosage in cats
How do we keep ivermectin out of the CNS?
By p-glycoprotein efflux pump- GABA agonist
What is the MOA?
GABA receptor agoinst
What is the main clinical sign?
CNS DEPRESSION!!
Most frequent- mydriasis (dilated pupils), blindness esp in cats, vomiting, drilling, weakness, stupor, recumbency, ataxia, coma
How do you diagnose Ivermectin toxicosis?
By Hx, clinical presentations
Also by exclusion– exclude other CNS depressant toxins (ethanol, methanol, ethylene, glycol, AMITRAZ)
What is the treatment?
No specific antidote
Decontamination
Supportive care
What is the prognosis?
Depends on exposure
If clinical signs are rapid- high level of exposure
No long term adverse effects if patient survives
