Lecture 22 Flashcards
What is the mechanism of action of praziquantal?
increases the influx of calcium and the release of calcium stores in the cestode. This causes neuromuscular toxicity and paralysis
Describe the spectrum of activity of praziquantal?
It is the gold standard against cestodes. Some activity against trematodes but very poor against the nematodes.
How safe is praziquantal?
Good - has a high margin of safety considered to be a very safe drug
What is the mechanism of action of closantel?
spastic paralysis
What is the spectrum of activity of closantel?
Liver fluke and Barbers pole worm (Haemonchus contortus)
Good activity against trematodes (flukes) and some activity against nematodes (haemonchus contortus)
What is an example of a benzimidazole?
Fenbendazole and triclabendazole
How to the benzimidazoles work?
Binds to B-tubulin this then inhibits micro-tubule formation which then disrupts cell division and maintenace of cell shape
What is the spectrum of activity of the benzimidazoles?
‘Broad spectrum’ anthelmintic - adult nematodes, weak against the trematodes, cestodes (weak)
Why is there resistance against benzimidazoles?
The rumen acts as a reservoir for the drug prolonging the duration of action. This explains the resistance within ruminants.
Provide an example of tetrahydropyrimidines and state their mechanism of action:
Example: pyrantel and oxantel
The cause spastic paralysis of the nematodes
What species are the tetrahydropyrimidines mainly used in?
Mainly used in small animals - very safe for puppies and kittens
What is the extent of resistance for the new drugs monepantel and derquantal and abamectin?
Being a new class of drug the extent of the resistance is quite minimal
What is the spectrum of activity of derquantel and abamectin?
Excellent efficacy against haemonchus contortus, trichostrongylus and nematodirus
Limited efficacy (less than 95% against telodorsagia)
