Anthelmintics

Question 1

1-BZ

Answer 1

Benzimidazoles
Binds to beta tubulin inhibiting polymerization
Given as suspension, paste or bolus
Lipid diet increases absorption

Question 2

Febantel

Answer 2

Benzimidazole
Prodrug
—> fenbendazole and fenbendazole sulphoxide
Effective against intestinal nematodes, lungworms and tapeworms

Question 3

2-LV

Answer 3

Levamisole
Nicotinic receptor agonists
Prolonged activation of excitatory Nicotinic Ach receptors —> spastic muscle paralysis

Question 4

Imidazothiazoles

Answer 4

Levamisole
Highly water soluble
Good tissue distribution oral parental topical
Rapidly cleared by kidney
Lung and GI nematodes

Question 5

Tetrahydropyrimidines

Answer 5

Levamisole
Eg pyrantel and morantel
Administered at tartrate and pamoate salts

Question 6

Pyrantel

Answer 6

Levamisole
Tetrahydropyrimidine
Poor GI absorption
Withdrawl period required for meat

Question 7

Morantel

Answer 7

Levamisole
Tetrahydropyrimidine
Sustained release from ruminal bolus
Safer drug- no withdrawl for dairy

Question 8

3-ML

Answer 8

Macrocyclic lactones

16 membered macrolide ring

Question 9

Avermecins

Answer 9

3-ML
Eg ivermectin
Activates glutamate gated chloride channels at NMj
Cl influx = hyperpolarisation = inhibition of contraction = flaccid paralysis
Particularly pharynx muscles
Well absorbed orally
All stages of nematode and ecto NOT trems or cests

Host mornally resistant due to p glycoprotein in brain capillery endo cells

Question 10

Milbemectin

Answer 10

3-ML
Broad spectrum
Works same as avermectin
Longer half life
Often given with praziquantel