Mechanisms of action of anti-parasite drugs

Question 1

Which NTs do antiparasite drug mimick the action of?

Answer 1

• Ach
• GABA
• Serotonin
• Glu
• Octopamine (OA)

Question 2

Give some examples of how antiparasite drugs can alter metabolic processes

Answer 2

• Inhibit microtubule synthesis
• Uncoupling of oxidative phosphorylation
• Inhibit chitin synthesis
• Inhibit DNA synthesis

Question 3

What are endectocides?

Answer 3

Combine activity against internal and external parasites, offering greater convenience and broader spectrum metazoan parasite control

Question 4

What are the different groups of anthelmintics?

Answer 4

Group 1: white drenches (BENZIMIDAZOLES)
Group 2: yellow drench (LEVAMISOLE)
Group 3: clear drenches (MACROCYCLIC LACTONES- AVERMECTINS/ MILBEMYCINS)
Group 4: Orange drench (MONEPENTAL- ZOLVIX)

Question 5

What is benzimidazoles mode of action?

Answer 5

Microtubule inhibitioin
-bind to tubulin which inhibits polymerization, affects homeostasis

(resistance: nucleotide change in target molecule leading to Aa substitution.

Question 6

Describe Levamisole

Answer 6

• Action is on the nicotinic Ach receptor
• Causes depolarisation and spastic paralysis
• Toxic to some dogs

Question 7

Describe macrocyclic lactones

Answer 7

• e.g. milbemycin/ avermectin
• Action is on the glutamate gated chloride channels, keeps them permanently open causing paralysis at pharynx, somatic muscle and uterus
• Collies are hypersensitive due to lack of P-glycoprotein
• Clinical signs= salivation, ataxia, mydriasis, tremor

Question 8

Which macrocyclic lactone drug is safe for collies?

Answer 8

Selamectin

Question 9

What is the mode of action of monepental?

Answer 9

• Binds to MPTL-1 receptors in NEMATODES
• Causing uncontrolled/ constant influx of ions
• Muscle cells depolarise causing paralysis

Question 10

What is the action of Emodepside?

Answer 10

-Binds to specific G-protein coupled receptors= flaccid paralysis of pharynx

Question 11

What is the action of praziquantel?

Answer 11

• Binds to B subunit of voltage gated calcium channels
  (not all helminths have this subunit so are not susceptible)
• Causes spastic paralysis
  -Vacuolation of tegument
  -GOOD FOR ECHINOCOCCUS