Antiparasitics Flashcards
What is the difference between drugs and pesticides?
Drugs have a DIN and pesticides have a PCP ACT registration number
True or False: Pesticides cannot be used in an extra-label manner
True
Why do antiparasitics not affect mammalian receptors?
Antiparasitics act as strong agonists of nematode receptors, but weak agonists of mammalian receptors
What is the most common reason for antiparasitic treatment failure?
Resistance
What are the three major classes of endoparasiticides?
- Benzimidazoles
- Imidazothiazoles/tetrahydropyrimidines
- Anti-cestodes
What are benzimidazoles, imidazothiazoles, and tetrahydropyrimidines effective against?
Nematodes
Which class of drugs target tubulin equilibrium?
Benzimidazoles
Name a common benzimidazole used in veterinary medicine
Fenbendazole
Which class of drugs are nicotinic receptor agonists and acetylcholinesterase inhibitors? What does this cause?
Imidazothiazoles/tetrahydropyrimidines. This causes spastic paralysis.
Name two common imidazothiazoles/tetrahydropyrimidines used in veterinary medicine
- Levamisole
- Pyrantel
Levamisole and pyrantel are _________ dependent
Concentration
What is pyrantel not suitable for?
Treating tissue stages of worms
What are the three major classes of ectoparasiticides?
- Pyrethrins/pyrethroids
- Isoxazolines
- Organophosphates and carbamates
What is the mechanism of toxicity of organophosphate/carbamate toxicosis?
Acetylcholinesterase inhibition
Organophosphates bind to acetylcholinesterase _______________ and carbamates bind _______________
Irreversibly, reversibly
What are endectocides?
Drugs that are active against internal and external parasites
What is the main class of endectocides?
Macrocyclic lactones
What are the two types of macrocyclic lactones? Name one example of each.
- Avermectins (ivermectin)
- Milbemycins (moxidectin)
True or False: Pyrantel is absorbed well from the GI tract
False, it is poorly absorbed
Describe the acute syndrome of organophosphate/carbamate toxicosis
- Will show muscarinic (DUMBBELLS) and nicotinic (tremors) signs
- Will show CNS effects
- Eventually death will occur from respiratory muscle paralysis
What is intermediate syndrome of organophosphate/carbamate toxicosis?
Occurs from chronic or prolonged exposure to pesticides, it results in development of muscarinic tolerance to overstimulation. This means clinical signs are due to nicotinic overstimulation. More common to see in cats but also observed in dogs and pigs.
Which class of drugs target voltage gated sodium channels?
Pyrethrin/pyrethroids (causes excessive depolarization and cell death)
Why is pyrethrin/pyrethroid toxicity more primarily a problem in cats versus dogs?
Metabolism of these insecticide compounds requires glucuronidation, and cats are not very good at that (so never give a dog antiparasitic to a cat)
What are the ligand-gated chloride channels?
GABA and glutamate
