Anthelmintics Flashcards
Define chemotherapy
Use of drugs to injure an invading organism without causing damage to the host (selective toxicity)
What 4 ways may anthelmintics be classified?
- Spectrum of acitivty
- Chemical group/mode of action
- Target parasites
- Method of delivery/formation
How can anthelmintics be classified based on spectrum of activity?
- Broad spec
- Narrow spec
Give an eg. of a narrow spec anthelmintic
Praziquantel - only used for hydatid disease (echinococcus)
What are the 3 main active ingredient classes/modes of action of anthelmintics? Give egs of each.
- benzimidazoles (BZ) - fenbendazole (panacur)
- imadozothiazoles (LM) - levamisole
- Macrocytic lactones (ML) - ivermectin
What are the 3 parasite specific targets?
- nematodicides
- cestodicides
- trematodicides (flukicides)
What 3 methods of delivery/formation are available?
- Oral eg. drench/tablet/bolus
- Parenterally eg. injectable
- Topically eg. pour on, spot on
What are the 3 main subgroups of broad spec anthelmintics? What will these be referred to as by farmers?
Group 1. BZ - benzimidazoles = White drenches
Group 2. LV - Imadazothiazoles = Yellow drenches
Group 3. ML - Macrocytic lactones = Clear drenches
What are the 2 newer classes of broad spec anthelmintics? What are these used for?
Group 4 (AD) Group 5 (SI) - reserved for last resort to prevent resistance developing
What are the narrow spec anthelmintics indicated for?
When specific pathogen is diagnosed. eg. Fluke drenches, tapeworms etc.
What is the mechanism of action of benzimidazoles (Group 1)?
B tubulin binding inhibited - worm starves due to inhibition of glucose uptake
What is the mechanism of action of the majority of anthelmintics?
NT interaction -> paralysis
What is the mechanism of action of Group 2 (LV) Imidazothiazoles?
Ach Ag
What is the mechanism of action of macrocyclic lactones?
Modulate glutamate-gated Cl- channels
What is a white drench?
Benzimidazoles
Give some examples of white drenches (benzimidazoles)
Albendazole, ricobendazole, fenbendazole, flubendazole, menbendazole, oxfendazole, triclabendazole