anthelmintics Flashcards
how many classes of anthelmintics are there for sheep?
5
considerations for anthelmintics
spectrum of activity
dosage
pharmacokinetics (absorption and excretion of drugs)
formulation and administration of drug
generic vs label claim product
drug efficacy and drug resistance
toxicity and specificity
cost
name the anthelmintic classes
benzimidazoles
imidathiozoles, tetrahydropyrimidines
macrocyclic lactones
amino acetonitrile deriatives
spiroindoles
action of benzimidazoles
bind to microtubule subunit protein - beta tubulin
inhibit microtubule mediated transport of secretory vesicles - prevents transport, enzymes released
Bzs spectrum of activity
not well absorbed systemically
primarily target nematodes
imidathiazoles action (2-LV)
act on nicotinic acetyl choline receptors
- somatic muscle cells
- paralysis and expulsion
imidathiozoles (2-LV) spectrum of activity
not well absorbed systemically
primarily targets nematodes
gut dwelling stage
short acting
macrocyclic lactones mode of action
highly lipophilic
following administration they are stored in fat tissue where they are slowly released
act on nervous system of parasite
potentiators causing hyperpolarisation
MLs spectrum of activity
well absorbed systemically
effective against nematodes only
target multiple nematode stages
residual activity
ENDECTOCIDE - target internal and external parasites
AAD modes of action
similar to 2-LV
acts via distinct nAChR
effective against parasites resistant to BZ, LV and MLs
target is nematode specific
AAD spectrum of activity
targets adults and L4 larvae of the most important species
primarily targets nematodes
relatively short acting - NO RESIDUAL ACTIVITY
spiroindoles action
derquentel blocks cholinergic neuromuscular transmission = paralysis and expulsion
spiroindoles spectrum of activity
narrow spectrum - effective against GI nematodes of sheep
gut dwelling stage only
ineffective against roundworms outside digestive tract
short acting
