Lab 1 - nematode pharmacology Flashcards
Name the “big three” antiparasitic agents for treating nematode infections.
Macrocyclic lactones
Benzimidazoles
Nicotinic agonists
What is the mode of action of the macrocyclic lactones?
Bind glutamate-gated chloride ion channels, opening them and eventually causing paralysis in the parasite.
Avermectins and Milbemycins belong to which major class of antiparasitic drugs?
Macrocyclic lactones
List the species and/or breeds that may experience toxicity from Ivermectin.
Collies, when used at doses higher than for heartworm prevention.
Turtles
Why are certain species of dog vulnerable to Ivermectin toxicity?
GABA-gated chloride ion channels in mammals are found in the CNS. In normal animals, the drug is pumped out of the blood-brain-barrier by permeability glycoprotein (P-gp).
Collies and some other dog breeds have a mutant P-gp that allows neurotoxicity to occur.
List the helminths against which macrocyclic lactones have no effect.
Cestodes
Trematodes
In which clade might you find glutamate-gated chloride channels?
Only in the protostome invertebrate phyla.
This is why you can treat mammals with Ivermectin and only see toxic effects in their parasitic nematodes.
What is the mode of action of the benzimidazoles?
Binds beta-tubulin, preventing microtubule formation and treadmilling. This in turn prevents cell division.
Why are benzimidazoles not toxic (for the most part) in mammals?
Benzimidazoles have a higher affinity for nematode beta tubulin than mammalian beta tubulin.
Fenbendazole, Oxfendazole, Albendazole, and Febantel are examples of what major class of antiparasitic drug?
Benzimidazoles
Which benzimidazoles can have teratogenic effects on a fetus?
Albendazole
Oxfendazole
Febantel is a pro-drug (i.e. metabolized into drug components) for which two benzimidazoles?
Fenbendazole
Oxfendazole
Against which other organisms does fenbendazole have activity?
Protozoa
Flatworms
Against which other organisms does Albendazole have activity?
Protozoa
Flatworms
What is the action of Nicotinic Agonist drugs?
Activates nicotinic ACh receptors, opening ion channels and causing muscle contraction, leading to paralysis in the worm.
Levamisole, Pyrantel, and Morantel are examples of which major class of antiparasitic drug?
Nicotinic Agonists
In which species is Levamisole used?
Ruminants
Pigs
In which species is Pyrantel used?
Dog
Cat
Horse
Pig
In which species is Morantel used?
Ruminant
Against which nematode are the Nicotinic Agonists ineffective?
Trichuris (whip worms)
Nicotinic Agonists may have some activity against which other helminths?
Cestodes in horses (?)
Name the “three little drugs” used in treating nematode infections.
Emodepside
Piperazine
Dichlorvos
What is the mode of action of Emodepside?
Agonist of presynaptic latrophilin receptor (which is a GPRC), which causes increased release of inhibitory neuropeptides.
The net result is paralysis
Emodepside is used for nematode treatment in which species?
How is it administered?
Cats
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